BUREAU OF ECONOMIC GEOLOGYTheUniversityof Texas

Austin,Texas

Peter T. Flawn, Director

Report of Investigations No. 50

Lignites of theTexas Gulf Coastal Plain

By

W.L.Fisher

October 1963

BUREAU OF ECONOMIC GEOLOGYTheUniversity of Texas

Austin, Texas

Peter T.Flawn, Director

Report of Investigations No. 50

Lignites of the

Texas Gulf Coastal Plain

By

W. L.Fisher

October 1963

Frontispiece

Operation of McKay Lignite Mining Company, Como, Texas(August 1913)

Report of Investigations No. 50

iContents

Page

ABSTRACT 1INTRODUCTION 2

Purpose of report 2Acknowledgments ZDefinition and geologic formation 2Geologic and geographic distribution 5History of mining 5Economic considerations. .. " " 7Production inTexas 8

GENERAL FEATURES OF TEXAS LIGNITES 9Regional variation 9

Ash content . " 9Calorific values . 9Fixed carbon content .. ,. 13Volatile matter content 13Fixed carbon/volatile matter content 13Sulfur 13Specific gravity 16Thickness of seams 16Features without significant regional variation 16

Reserves 19Utilization 19

OCCURRENCE OF TEXAS LIGNITE 24Wilcox lignites , 24

Anderson County . .. 25Atascosa County 26Bastrop County , 26Bexar County 35Bowie County 36Caldwell County. , 37Camp, Franklin, and Titus counties , 38Cass County 38Freestone County. 40Gregg County 40Guadalupe County 40Harrison County 0 42Henderson County 47Hopkins County 48Lee County 50Leon County . 51Limestone County 53Marion County 54

ii

Page

Medina County 54Milam County 57Morris County " . . 62Nacogdoch.es County 63Panola County 64Rains County. 67Robertson County . . 67Rusk County ....'. 70Shelby County . 70Smith County. .."-." 72Uvalde County 74Van Zandt County 75Wood County . 76Zavala County . 78Miscellaneous Wilcox lignites ,. 80

Yegua lignites ............... 80Angelina County ... 80Atascosa County 80Houston County ... " 81McMullen County ....... 0 . 84Miscellaneous Yegua lignites , 85

Jackson lignites o .......... 85Fayette County 87

Mt. Selman lignites ............... 92Atascosa County 92Mt. Selman cannel coals 92

BIBLIOGRAPHY , . " . 93APPENDIX A. ANALYSES OF TEXAS LIGNITES 104

Introduction .,.. . 104Proximate analyses 105Ultimate analyses 115Description of samples 118

APPENDIX B. LIGNITE MINES IN TEXAS 146

iii

Illustrations

Page

Operation of McKay Lignite Mining Company at Como, Texas . . . FrontispieceFigures--

1. Distribution of principal lignite-bearing rocks in Texas . 0 . . 62. Lignite production in Texas. . . , ....... 83. Regional variation in ash content of Texas lignites . . . . 114. Regional variation in calorific values of Texas lignites . . .. 125. Regional variation in fixed carbon content of Texas lignites . 146. Regional variation in volatile matter content of Texas

lignites . . " " 157. Regional variation in sulfur content of Texas lignites . . . . . 178. Regional variation inspecific gravity of Texas lignites .... 189. Distribution of Wilcox lignites inAnderson County ...... 24

10. Distribution of lignite-bearing rocks in Atascosa County ... 2511. Distribution of lignite deposits inBastrop County . 2612. Log of test boring at Glenham Station, Bastrop County .... 2713. Diagrammatic section of bluff opposite Powell Bend,

Colorado River , 2914. Diagrammatic section of lignite inCedar Creek, Bastrop

County 3015. Diagrammatic section of lignite inPiney Creek, Bastrop

County 3116. Diagrammatic section of lignite in Dennison Creek, Bastrop

County 3217. Diagrammatic section of lignite in Elliot Pit No. 5, Bastrop

County 3318. Diagrammatic section of lignite inpit at Dunstan Station,

Bastrop County 3419. Distribution of lignite deposits inBexar County . . 3520. Distribution of Wilcox Group in Bowie County 3621. Distribution of Wilcox Group in Caldwell County 3722. Distribution of Wilcox Group in Camp, Franklin, and

Titus counties 3923. Distribution of Wilcox lignites inCass County 3924. Distribution of Wilcox lignites inFreestone County 4125. Distribution of Wilcox Group in Gregg County 4126. Distribution of Wilcox Group in Guadalupe County 4227. Distribution of Wilcox lignites inHarrison County 4328. Diagrammatic section, Robertson Ford, Harrison County . . 4329. Diagrammatic section, Darco mines, Harrison County .... 4430. Distribution of Wilcox lignites in Henderson County 4731. Distribution of Wilcox lignites in Hopkins County . 4832. Sectionof lignite mined by Como Coal Company, Hopkins

County 4933. Distribution of lignite deposits in Lee County 50

iv

Figures--

34. Distribution of Wilcox lignites in Leon County 5235. Distribution of Wilcox lignites in Limestone County 5336. Distribution of Wilcox lignites inMarion County 5437. Distribution of Wilcox Group in Medina County 5538. Logs of mine shafts of Carr and Riley mines, Medina County . 5639. Distribution of Wilcox lignites inMilam County 5740. Log of shaft ofRockdale Mining Company, Milam County.... 5841. Diagrammatic section, strip mine of Industrial Generating

Company, Milam County 5942. Distribution of Wilcox lignites inMorris County . . . 6243. Distribution of Wilcox Group in Nacogdoches County 6344. Distribution of lignite deposits in Panola County 6445. Diagrammatic section ofBlack Shoals, Panola County 6546. Diagrammatic section of shoals on Sabine River 6647. Distribution of Wilcox lignites inRains County . 6748. Distribution of lignite deposits inRobertson County 6849. Diagrammatic section, Calvert Bluff, Robertson County .... 6950. Distribution of Wilcox Group in Rusk County 7151. Distribution of Wilcox Group inShelby County 7152. Distribution of Queen City Formation in Smith County 7353. Distribution of lignite deposits in Uvalde County 7454. Distribution of Wilcox Group in Van Zandt County 7555. Distribution of lignite deposits inWood County 7756. Distribution of lignite deposits in Zavala County 7857. Diagrammatic section of lignites on Nueces River, Zavala

County 7958. Distribution of Yegua Formation inAngelina County. ...... 8159. Distribution of Yegua Formation inHouston County 8260. Diagrammatic section, Hydes Bluff, Houston County 8361. Sectionof lignite mined at Wooters Station, Houston County . . 8362. Distribution of Yegua lignite deposits in MeMullen County ... 8463. Diagrammatic section of lignite deposits on San Miguel

Creek, MeMullen County 8664. Distribution of Manning lignites in Fayette County 8765. Log of shaft mines south of Ledbetter, Fayette County 8866. Diagrammatic section, Mantoon Bluff, Fayette County 8967. Diagrammatic section of lignites onO'Quinn Creek, Fayette

County 91

Tables--

1. Average composition of Texas lignites 42. Stratigraphic distribution of lignite in Texas 33. Principal lignite deposits in Texas.. 104. Total estimated reserves of lignite inEocene rocks of Texas . 205. Estimated reserves of lignite in Texas, by county 21

Lignites of the Texas Gulf Coastal Plain

W. L. Fisher

Abstract

One of the basic mineral resources of Texas is abundant deposits of lig-nite in Eocene rocks of the Gulf Coastal Plain. Currently, Texas lignites areutilized as sources of industrial fuel, activated carbon and, locally, drilling-mud additives; research indicates significant future nonfuel uses of lignite andlignitic coals.

Principal deposits of lignite in the Texas Gulf CoastalPlain occur in theWileox Group and locally in the Yegua and Manning Formations. Southwestwardalong the outcrop, lignites increase in content of ash, decrease in content ofvolatile matter and fixed carbon, and decrease in calorific value. Highestquality lignites generally occur in the Wilcox Group in the area northof theColorado River. Yegua and Manning lignites, and Wilcox lignites south of theColorado River, are characterizedby relatively high ash content.

Existing estimates of lignite reserves in Texas are generalized owing tolack of data. Latest estimates list total recoverable, measured, and indicatedreserves at approximately 4.3 billion short tons.

Principal deposits of lignite occur in the following areas: (1) southernTitus County, (2) east-central Hopkins County, (3) southwestern Wood andsoutheastern Rains counties, (4) south-central Van Zandt County, (5) westernHenderson County, (6) southern Harrison and northwestern Panola counties,(7)northwesternShelbyandnortheasternNacogdochescounties, (8) northwesternLeon and southern Freestone counties, (9) southeastern Houston and north-central Trinity counties, (10) southwestern Houston County, (ll)Milam andnorthwestern Robertson counties, (12) central Bastrop County, (13) centralFayette County, (14) junction of Medina, Bexar, and Atascosa counties, (15)north-central Atascosa County, and (16) northwestern McMullen and south-central Atascosa counties.

1

2Introduction

Purpose of Report

Primary purpose of this report is to outline general features of Texaslignites as an aid to possible future exploitation and utilization. In the past,Texas lignites were used primarily as fuel; at present, lignites are used inTexas as an industrial generating fuel, as a source of activated carbon, and,in the weathered or oxidized state, as a drilling-mud additive. Results of re-cent research indicate that future nonfuel as well as specialized fuel uses oflignite should be significant.

Acknowledgments

The writer expresses appreciation to P. T. Flawn, Director, Bureau ofEconomic Geology, The University of Texas, for support and interest in thecourse of this study and for reading critically the manuscript; and to D.W.Kohls and P.U. Rodda, Bureau of Economic Geology, for reading the manu-script and offering helpful suggestions. Data previously compiled by' H.B.Stenzel, J. T. Lonsdale, J. T. Twining, and J.M. Perkins, all formerly withthe Bureau of Economic Geology, have been utilized in this report. R.A.Maxwell, Bureau of Economic Geology, provided information concerning lig-nites of southern Texas. W. J. van Reenan and G.H. Scheffler, of Atlas Chemi-cal Industries, Inc., and personnel of Industrial Generating Company providedinformation on current production, utilization, and quality of Texas lignites.Burke Burkhart ably assisted with field work.

Definition and Geologic Formation

Coals are formed by biochemical and physical processes acting on ac-cumulated plant material. Nature and composition of coal depend on (1) theoriginal composition or type of accumulated plant remains and (2) the durationandcharacter of geologic processes that acted upon accumulated plant remains.These factors are reflected indifferent ranks of coal: (in increasing order ofrank) peat--lignite (or brown coal) --bituminous coal- -anthracite. Rank ofcoal within this sequence is distinguished primarily by difference in texture,petrographic and chemical composition, and calorific value.

Lignite represents an early stage of coal formation and contains more orless clearly separable pieces of plant material. Most lignite is soft andfriable, has a low specific gravity, and is comparatively porous. Based onpetrographic composition, lignite is dividedinto two types --attrital and xyloid.Attrital lignite is composed largely of residual remains of plant matter thatwere macerated or mechanically broken to microscopic fragments duringearliest stages of coalification. Certain decay-resistant parts of plants

3constitute large parts of some attrital lignites. Attrital lignite is nonbandedand has a uniform, fine-grained texture. Xyloid lignite differs from attritallignite in containingmore than 50 percent anthraxylon, a material derived fromwoody parts of plants. Xyloid lignite is generally banded, and original plantstructures are well preserved. Most Texas lignite is of the xyloid type, al-though it commonly contains considerable amounts of attritalmaterial.

A recent international classification of low-rank coals, such as Texaslignites, is based on (1) total moisture which is related to calorific value andso is indicative of fuel value and (2) yield of low-temperature tar which indi-cates value of lignite for chemical processing.

Average analyses of Texas lignites are given in table 1 (p. 4). Averagesof proximate analyses based on fewer than five analyses are indicated by anasterisk.

Table 2. Stratigraphic occurrence of lignite deposits in TexasGulf Coastal Plain. (Main occurrences noted by asterisk.)

Period Series Group and Formation

PlioceneNeogene

Miocene

Oligocene

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* ManningJackson

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Caddell

Yegua

Cook Mountain

(NE Texas) (S Texas)

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artaec es

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Fig. 3. Regional variation in ash content of Texas lignites. (Percent ash,dry basis. )

12

Fig. 4. Regional variation in calorific values of Texas lignites. (B.t.u. /pound, dry basis.)

13

Fixed carbon content. --Fixed carbon content of Texas lignites averages37%, with highest values north of the Colorado River (fig. 5), Areas with lig-nites of high fixed carbon content coincide with areas having lignites of highcalorific values. Fixed carbon content in Wilcox lignites varies from 30% to50% inareas north of the ColoradoRiver to less than30% south of the ColoradoRiver. Fixedcarbon contentofUpper Eocenelignites alsodecreases southward,averaging 30% to 40% in east Texas and less than 30% in south Texas.

Volatile matter content. --Texas lignites are characterizedby a generalsouthward decrease in content of volatile matter (fig. 6). Regional decrease involatile matter content corresponds withincrease in ash content. Lignites withhigh volatile matter content (exceeding 50%) occur in the following areas: (1)Trinity River to Sabine River, (2) Franklin to Bowie counties, (3) southernpart of Sabine Uplift, (4) Bastrop County, and (5) Houston and Trinity counties;medium values (40% to 50%) occur in (1) Rains, Wood, and Hopkins counties,(2) northern part of Sabine Uplift, (3) Lee County to Trinity River, (4) FayetteCounty, and (5) Medina to Caldwell counties;low values (less than 40%) charac-terize Lower and Upper Eocene lignites of south Texas.

Fixed carbon/volatile matter content, --Ratio of fixed carbon to volatilematter content (ash-free) is highest in Wilcox lignites north of the ColoradoRiver and lowest in Upper Eocene lignites and Wilcox lignites south of theColorado River,, Variations in this ratio indicate changes in Texas lignitesother than those caused by changes in ash content. High ratios occur in theSabine Uplift and from Milarn County north to the Trinity River; these valuesrepresent lignites with highest calorific values. Medium ratios characterizeWilcox lignites northeast of the Trinity River and Bastrop and Lee counties;lowest ratios occur in lignites with low calorific values in the Wilcox Group ofsouth Texas and throughout the Yegua and Manning Formations.

Sulfur. --Wilcox lignites contain less than 1.0% sulfur, on anas-receivedbasis, in most areas north of the Colorado River; locally, lignites occurringbetween the Brazos and Trinity Rivers contain 1.0% to 1.5% sulfur. Sulfurcontent inWilcox lignites south of the Colorado River increases to 2.0% (fig. 7).Upper Eocene lignites vary from less than 1.0% in east Texas to 2.0% in southTexas.

14

Fig. 5. Regional variation in fixed carbon content of Texas lignites. (Percent fixed carbon, dry basis.)

15

Fig. 6. Regional variation in volatile matter content of Texas lignites.(Percent volatile matter, dry basis.)

16

Specific gravity. --Specific gravity of Texas lignites ranges from 1.2 to1.4 (fig. 8). Where lignites have uniform ash content, highest specific gravityoccurs in samples with highest fixed carbon content and calorific values. Lig-nites with lower specific gravity occur in Wilcox rocks north of the TrinityRiver and south of the Colorado River,, Lower specific gravity of lignites innortheast Texas coincides with lignites of relatively high fixed carbon contentbut with low ashcontent; lignites in south Texas have a specific gravity similarto those ofnortheast Texasbut have relativelylow fixed carbon content and highash content.

Thickness of seams. --Lignite seams characteristicallyarelenticular andirregular; few individual seams have an arealextent exceeding 10 square miles.Lignite seams aremuch thinner andoccur with more numerous partings in southTexas than in east Texas. Partings generally consist of clay or shale, "black-jack," "bone," or "rotten coal." In general, thicker and more extensive seamsof lignite are more uniform in character and higher in quality than thinner andmore irregular seams.

Features without significant regional variation. --Average moisture con-tent of Texas lignites is about 30%, on an as-receivedbasis, but there is littlesignificant regional variation inmoisture content. Moisture content in lignitesis important, however, in that it affects the calorific value. This importanceis demonstrated in the following example comparing average values of lignitesfrom Wood and Milam counties:

Average moisture, % Average B. t.v. /lb. Average B. t.v. /lb.(as-receivedbasis) (as-received basis) (drybasis)

Milam County 30 7,500 11,150Wood County 26 7,960 10,750

Lignites fromMilamCounty have a higher average calorific value on drybasisthan those from Wood County but have lower average calorific values on as-received basis due to higher moisture content. Difference in calorific valueson dry basis is due chiefly to difference in fixed carbon content; ash content oflignites from the two areas is similar.

Carbon, hydrogen, nitrogen, and oxygen content, determined inultimateanalyses, shows little significant regional variation. However, on an ash-freebasis, higher carbon and hydrogenand lower oxygen content occurs in ligniteshaving higher calorific values.

17

Fig. 7. Regional variation in sulfur content of Texas lignites. (Percentsulfur, as-received basis.)

18

Fig.8. Regional variation, in specific gravity of Texas lignites (as -receivedbasis).

19

Reserves

Strata containing lignites occurring at varying depths occupy an area inTexas estimated at 60,000 square miles. Estimates of the quantity of lignitewithin this area have ranged from Bto 30 billion tons. Two factors seriouslyinhibit reliable determination of lignite reserves in Texas: (1) lack of controldata and (2) different distinctions of commercial and noncommercial deposits.Early estimates, includinga figure of23billion tons by Campbell (inHendricks,1939), were highly generalized because of limited data and calculations basedon partly unwarranted assumptions. The most recent and probably most re-liable estimate of lignite reserves in Texas is that of Perkins and Lonsdale(1955) who gave measured and indicated reserves as approximately 7 billiontons, notingrecoverable reserves on the order of4.3billiontons (table4, p. 20).

In estimating reserves of Texas lignites, Perkins and Lonsdaleattemptedto assemble all available records of lignite inTexas, andas such their estimateis inaccord with available known facts. Their estimate is, of course, a con-servative one in that it included onlymeasured and indicated reserves and notinferredreserves. Tomake their estimatemore specific than earlier estimates,these writers took into account (1) lenticular nature of lignite deposits, (2)occurrence of ground water, (3) commercial thickness, (4) amount of over-burden, and (5) average recovery in open-pit versus undergroundmining. Indi-catedreserves were determined by assuming an area with a radius of 0.5 mile(measuredreserves assume a radius of mile) for eachoccurrence of alignitebed 5 feet or more thick and at depths less than 500 feet; average specificgravity was assumed to be 1.2. Various private estimates indicate profitablereserves of lignite in Texas are much less than early estimates and probablyare on the order of the estimate of Perkins and Lonsdale.

Estimated reserves by county (computedby J.M. Perkins and on file atBureau of Economic Geology) are given in table 5 (p. 21).

Utilization

Lignite may be used (1) directly as a solid fuel, (2) both as a fuel and asa source of chemicalproductsbycarbonization and recoveryof tars andliquids,or (3) solely as a source of chemical products by conversion through hydro-genation or gasification. Various uses of lignite are summarized in some de-tail inInformationCirculars 7691and 76920f theU. S. Bureauof Mines (1954a,b).

As a direct solid fuel, lignite is a low-energy source and is utilizedasany bulk raw material. With carbonization, lignite yields certain chemicalproducts in the form of a liquid fraction, anda fuel in the form of a low-B. t. v.gas and a solid residue. In Texas lignites, the solid residue is considerableso that a fuel demand must exist to make the carbonizationprocess economi-cally attractive. Products of the liquid fraction from carbonization depend

20

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TABLE 5. Estimated reserves of lignites in Texas Gulf Coastal Plain,bycounty;file atI

figures3ureau o:

inHi

millions

conomic (of

Geoshort

"logy)*tons (computedby J.M. Perkins; data on

file at Bureau of Economic Geology).

Measured ReservesMeasiureid Resesrves Indicated ReservesThin Thick Thin Thick

County overburden* overburden overburden overburdenWILCOX LIGNITES

Anderson 21.4 55.2 64.2 165.6Bastrop 54.8 86.4 153.9 348.2Bexar 15.5 28.6 46.5 85.8Bowie 47.4 2.0 10.2 6.0Caldwell 38.0 59.2 114.0 177.6Camp 6.8 20 20.4 6.0Cass 17.9 21.6 53.7 64.0Cherokee 11.0 34.6 33.0 67,8Franklin 3.0 4.0 9.0 12.0Freestone 25.5 23.8 76.5 71.4Gregg 4.1 32.0 12.3 96.0Harrison 46.8 17.8 76.8 53.4Henderson 37.8 33.0 113.4 99.0Hopkins 24.1 6.0 61.8 18.0Lee 6.2 11.2 18.6 33.6Leon 24.4 18.0 73.8 54.0Limestone

--6.2

--18.6

Marion 11.1 16.0 33.0 48.0Milam 254.6 2.0 163.8 6.0Morris 5.5 3.4 16.5 10.2Panola 35.1 17.0 105.3 51.0Rains 3.6 5.6 10.8 16.8Robertson 28.1 26.0 84.3 78.0Rusk 41.6 104.4 124.8 313.2Shelby 18.6 10.0 55.8 30.0Titus 36.5 10.0 109.5 30.0Van Zandt 69.3 34.4 207.9 103.2Wood 38.5 33.6 94.5 100.8

YEGUA AND JACKSON LIGNITESAngelina 5.1 7.6 15.3 22.8Brazos 2.8 6.0 8.4 18.0Burleson 4.0 17.8 12.0 53.4Fayette 27.0 5.4 81.0 16.2Grimes 12.8 19.8 38.4 59.4Houston 16.9 29.2 50.7 87.6Madison 7.6 5.0 22.8 15.0Nacogdoches 4.5 16.2 13.5 348.6San Augustine

--1.0 -- 3003 o0

Trinity 6.1 13.8 18.3 41.4Walker 7.9 11.0 23.7 33.0Washington 5.4 22.0 16.2 66.0

*Thin overburden, less than 90 feet; thick overburden, greater than 90 feet.

22

upon the initial composition of the lignite and especially upon the temperatureof carbonization. Present research on carbonization of lignite is centeredaround efforts to obtain the best features of both high- and low- temperatureprocesses, and the utilizationof certain specialized carbons derived from lig-nites. Liquid products, which represent about 6.7 percentby weight in Texaslignites, include (1) simple aromatic compounds (benzene, toulene, xylene, andnapthalene); (2) aromatic tar acids (phenol, cresole, and xylenol);(3) tar bases,primarily pyridine; (4) minor amounts of high molecular weight constituentsfor specializeduses in synthesis ofdyestuffs andPharmaceuticals;and (5) large,complex fractions for crude creosote, road tar, wood preservative, and bi-tuminous coating. The U.S. Bureau of Mines (1962) reported carbonizationassays of 18 cores of six different lignite seams from east Texas which indi-cated an averageyield of 56.3 percent char and18.6percent tar -plus-light-oil,on a moisture- and ash-free basis. Tar yield was equivalent to approximately17.3 gallons per ton of as-mined lignite. Low-temperature tars from Texaslignites are stable enough in chemical character to be processed in a con-ventional tube heater and flash fractionator. Byaltering distillation conditions,yields of hard carbon pitch can be varied from 38 to 60 percent.

Utilization of lignite through processes of hydrogenation or gasificationresults in a complete conversion of the lignite, and production does not requirea market for fuel. Hydrogenation involves the use of hydrogenunder pressureforpartial breakdown of the coalcomplex into lower molecular weightproducts;chief productsare certain aromatic chemical compounds. Gasificationinvolvesthe complete breakdown of hydrocarbons to carbonmonoxide and hydrogenbypartialcombustion or gasification, followed by reintegrationof these materialsinto desired end-products, such as ammonia, nitric acid, methanol, and form-aldehyde. These products are in turn used inpart for such chemical hydro-carbon end-derivatives as plastics, elastomers, synthetic fibers, detergents,and bulkagricultural chemicals. Results of hydrogenation tests of Texaslignitefrom Rockdale, Texas, are reportedby Hiteshue et al. (1962).

Leonardite, formed through either natural or artificial weathering oroxidation of lignite, is used as a dispersant, for viscosity control inoil-fielddrilling muds, as a stabilizer for ion-exchange resins in water treatment, andas a source ofwater -solublebrown stainfor wood finishing (Fowkes and Frost,I960); itmayalsobe a source ofhumic acids. Little is known of the occurrenceof leonardite in Texas, though it is commonly associated with lignites of thewestern interior of theUnited States.

Rare trace elements commonly are concentrated in carbonaceous rocks.Trace elements in ash of Texas lignites have been studied by Deul and Annell(1956), who reported analyses of 48 samples of lignite from Milam County,Texas; Kohls (1962) gave trace-element determinations of 6 samples of Texaslignites; Stadnichenko et al. (1961) reported beryllium content of ash fromHarrison County lignites. General conclusion of these writers is that traceelements of Texas lignites are not anomalously concentrated relative to otherknown coals and lignites.

23

Extractable -waxes from Texas lignites havebeen reportedby Selvig et al.(1950), who indicated yields lower in Texas xyloid or woody lignites than fromattrital lignites of certain other areas in the United States.

Activatedcarbons derivedfrom lignite are used fordecolorizing solutions,water treatment, recovery of solvents, gas absorption, recovery of gold, andextraction of iodine. The Darco Plant of Atlas Chemical Industries, Inc.,located atMarshall inHarrison County, processes activatedcarbon from Texaslignite. This operation is the only commercialplant in theUnitedStates makingactivated carbon from lignite. Production of activated carbon from Texas lig-nites has been discussed by Evans (1944).

Results of research and technologic work on coal and lignite, conductedby the U.S. Bureau of Mines and certain private organizations, are reportedperiodically as Information Circulars of the U.S. Bureau of Mines (c.g., Nos.7904, 7905, 7970, 8098, 8119).

Utilization of lignite is possible in almost any chemical or industrialprocess requiring carbon or carbon compounds. Future utilization of Texaslignites will depend upon a number of economic factors, but the plentifulreserves of this mineral resource make it potentially important in diverseareas of future industrial development.

24-

Occurrence of Texas Lignites

Wilcox Lignites

The most important and extensive deposits of lignite in Texas occur inthe Wilcox Group which,in the central and part of the northeastern Texas GulfCoastalPlain, is divided into the following formations:

SabinetownFormationCalvert Bluff FormationSimsboro FormationHooper FormationSequinFormation

Within this area, the main lignite deposits occur in the lower part of the Cal-vert Bluff, or near the middle of the Wilcox Group. In areas where the WilcoxGroup is not divided into formations, lignite deposits also generally occur inthe middle or upper part of the group.

Fig. 9. Generaldistribution of Wilcox lignites in AndersonCounty, Texas.

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Anderson County. --Significant deposits of Wilcox lignite occur locally inAnderson County where Wilcox rocks crop out in the northwestern corner ofthe county and concentrically around the Palestine salt dome (fig. 9) Thinand generallynoncommercial deposits of Queen City lignite in Anderson Countywere reported by Dumble (1892). Analysis of a 2-foot bed of Queen City lig-nitefrom Caddo Creek, 17 miles northeast of Palestine, is given inAppendixA.

Fromthe early1900's to about 1935, lignite was mined inAnderson Countyat the Palestine salt dome, located 6.4 miles west of Palestine. Mines wereoperated mostly by Palestine Salt and Coal Company, 1^ miles northeast ofDuggey Lake, which roughlymarks the center of the salt dome. Powers (1926,pp. 46, 51) reported three seams of lignite, each 7.5 feet thick and separatedby 25 to 30 feet of sandstone and shale. Most of the lignite was used locally asa fuel in the production of salt.

Fig. 10. General distribution of lignite-bearing rocks inAtascosa County,Texas.

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Atascosa County. --Wilcox rocks are exposed in the northern part ofAtascosaCounty(fig. 10),where lignites, similar to those in Bexar and Medinacounties, crop out and have been mined. Dumble (1892) reported mining southof Somersetat the oldKinney mine. He did not describe thelignite but indicatedit was similar to that mined at the Kirkwood mine on an adjoining property inBexar County where 5.5 feet of lignite was mined at a depth of probably lessthan 50 feet. Maxwell (1962, p. 87) has indicated that two or more seams ofWilcox lignite occur in northern Atascosa County at depths of 40 to 90 feet.

Bastrop County. --Important lignite deposits occur in Bastrop County inthe lower part of the Calvert Bluff Formation (fig. 11). Main areas of lignitedeposits in the county are: (1) vicinity of Butler, (2) vicinity of McDade, (3)divide area between Big Sandy and Piney Creeks from Sayersville to Bastrop,and (4) along Cedar Creek east of FarmRoad 20.

Fig. 11. Distribution of lignite deposits inBastrop County, Texas. Areaof principal deposits ruled.

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Previous mining in BastropCounty, largely alongthe Missouri-Kansas-Texas Railroad betweenSayersville and Bastrop and alongthe Missouri Pacific Railroad inthe vicinity of McDade, began in1886. Approximately 25 mineshave been operated, although nonehas been worked since about 1944.First mining was in small, openpits;subsequentandmore extensivemining was underground. In theold mining areas, two to threebeds of lignite were mined; thesewere generally known as beds #3,#4, and #5 (fig. 12). Dietrich andJLonsdale (1958, p. 60) reportedranges in thickness for these lig-nite beds as follows:

FeetBed #3 2.5 to 4.5Bed #4 3.5 to 5.0Bed #5 5.0 to 11.0

Numerous beds of lignite oc-cur in the HooperFormation in thewestern part of the county, butthesebeds arevery thin, lenticular,and probably not economically im-portant.

Fig. 12. Log of test boring drilledbyBastrop LigniteCompany near GlenhamStation on Missouri-Kansas-Texas Rail-road, north of Bastrop. Data from Die-trich and Lonsdale (1958, p. 60).

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Stratigraphic sections and descriptions of outcrops inBastropCounty aregiven in figures 13 to 18. Other outcrops in the county include:

1. West bank of Big Sandy Creek, J mile downstream from crossing ofState Highway 95 over Big Sandy Creek; 6.0 feet of lignite.

2. Banks of left tributary of Harris Creek, 0.3 mile southwest of inter-section of State Highway 95 and Farm Road 2336; 7.5 feet of lignitewith 1.5-foot clay parting.

3. Right bank of Colorado River, 3.3 miles by river from bridge ofState Highway 71 Bypass; 6.0 feet of lignite.

4. One and one-fourthmiles below Sandy Creek on Colorado River.5. Clay pit of Payne Brick Company, north side of county road turning

west of FarmRoad 696, at a point 3.6 miles north of Butler.

Standardanalyses oflignites fromBastrop County aregiven in Appendix A.Phillips and Worrell (1913, p. 202) recorded the following analysis of gasdistillate from lignite mined by Independence Mining Company at Phelan:

Gas yield, cv. ft. /ton . 8,135Illuminants, % 2.5Carbon monoxide, % . 9.0Hydrogen, % . ........... 46.4Methane, % 30.0Nitrogen, % . 10.0Specific gravity .474Candle power 3.4B. t.u. /cu. ft. (calc. ) . 524

29

Fig. 13. Diagrammatic section of lignite exposed on east bluff of ColoradoRiver, 0.5 mile south of gravel road from Phelan to Mt. Zion Church, at apoint 1.6 miles west of Phelan;oppositePowell Bend. Calvert Bluff Formation.

30

Fig. 14. Diagrammatic section of lignite exposed on north bank of CedarCreek, 0.2 mile downstream from bridge on Farm Road 20. Calvert BluffFormation.

31

Fig. 15. Diagrammatic section of lignite exposed on west bank ot PineyCreek, 200 yards upstream from Missouri-Kansas-Texas Railroad crossing.Calvert Bluff Formation.

32

Fig. 16. Diagrammatic section of lignite exposed on northbank of DennisonCreek, 0.6 mile upstream from Colorado River and 0.3 mile upstream fromcrossing of county road. Calvert Bluff Formation.

33

Fig. 17. Diagrammatic section of abandoned lignite pit, known as Elliotpit No. 5, at head of Dennison Creek. Calvert Bluff Formation. (Modifiedfrom notes of J.E. Elliott.)

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Fig. 18. Diagrammatic section of abandoned pit west of Dunstan Station,old landing on Missouri-Kansas- Texas Railroad, 4.4 miles north of center ofBastrop. Calvert Bluff Formation. (Modified from notes of J. E. Elliott. )

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Bexar County. --Wilcox rocks crop out in a belt extending across thesouthern part of Bexar County (fig. 19); these are the only rocks in the countyknown to contain lignite. Few outcrops of lignite are known, but lignites havebeen mined in the extreme southwestern part of the county at the old Kirkwoodmine andat a mine operated by Brackenridge Coal Company.

Schoch (1918, pp. 77, 189) gave analyses and location of an outcrop oflignite along the south side of the Missouri Pacific Railroad crossing of theMedinaRiver near Cassin. At this outcrop 4.5 feet of lignite is exposed, withan overburden of 40 feet. Drill holes in the vicinity of the outcrop, however,penetrated only 14 inches of lignite at 164 feet.

Fig. 19. General distribution of lignite deposits in Bexar County, Texas.

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The oldKirkwoodmine, locatedin the extreme southwesternpart ofexarCounty, about 3/4 mile north of the Atascosa County line, was operated duringthe late 1800's. Dumble (1892, p. 185) briefly described the lignite and notedthat the mined seam was 5.5 feet thick. Sellards (1920, p. 119) mentionedthat in1920 theBrackenridge Coal Company planned to start mining operations1.5 miles west of Somerset. Drilling in this area indicated a seam of lignite 5feet 9 inches thick at a depth of 44 feet.

Bowie County. --Potentially commercial deposits of Wilcox lignite occurinBowie County but little attempt has been made to develop them. Outcrops oflignite are reported along Sulphur River andAnderson Creek (fig. 20). Dumble(1892) reported shafts on Anderson Creek, 5 miles south of Boston, where a12 -foot seam of lignite was mined at a depth of 30 feet. Similar occurrencesof lignite are reported on the Cass County side of Sulphur River, e.g., the12-foot seam at Stone Coal Bluff. Lignite was mined from 1907-1909 by theCarbondale Coal Company, about 2 miles north of Carbondale. Core drillinginthe vicinity of the old mine indicated a lignite 3 to 13 feet thick with an arealextent of approximately 2,000 acres.

Fig. 20. Distribution of Wilcox Group inBowie County, Texas.

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Analyses of lignites from. Bowie County (Appendix A) indicate that theselignites are similar inquality to those to the south and southwest.

Caldwell County. --Lignite-bearing rocks of the Wilcox Group extendsouthwest across Caldwell County (fig, 21). Little is known of the thickness orquality of the lignites. Most reported occurrences are in the upper part oi theWilcox Group in the eastern part of the county. Lignites are recorded in sev-eral driller's logs andcrop out alongstreams in the eastern part of the county;exposures occur along SandyFork of Peach Creek in the extreme southeasternpart of the county and atBurdett Wells onClear Fork of Plum Creek, 5.2 milessouth-southwest of Lockhart. The onlyreported thickness of lignite inCaldwellCounty is recordedbyDumble(1892) from the vicinity of Pin Oak Creek, wherethree beds, each 1.5 to 2.0 feet thick, are exposed. Lignites exposed in thevicinity of Prairie Lea are in the lower part of the Wilcox Group.

Analyses of lignites from Burdett Wells are given in Appendix A,

Fig. 21. Distribution of Wilcox Group in Caldwell County, Texas. Areaof principal lignite deposits ruled.

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Camp, Franklin,and Titus counties. --Significantandcommercial depositsof Wilcox lignite occur in Camp, Franklin, and Titus counties. Past develop-ment has been mostly in Titus County with mining at Winfield, Mt. Pleasant,and Cookville. Outcrops, found mostly in streams and creeks, are commonwithin the area noted in figure 22.

Seven mines have been operated in Titus County. A

-to 8-foot seam of

lignite was mined at a depth of 50 feet by Cookville Coal & Lumber Companyat Cookville;LibbyManufacturingCompanymineda 7-foot seam at Mt. Pleasant;lignite mining was reportedat Winfield in 1931 by Plummer (1933), in 1934byBaker (1935), and in 1946 by Stenzel (1948). Baker (1935) reporteda shaft innorthwestern Camp County, near Newsome, with two seams of lignite 5.5 and4 to 5 feet thick being worked. Little is known of lignites in Franklin County,but they are probably similar to those in Titus and Camp counties.

Thickness and nature of the lignites inmines, as well as the indication ondriller's logs of lignites at shallow depths, show that commercial deposits oflignites are extensive in Camp, Franklin, and Titus counties.

Analyses of lignites from Titus and Campcounties are given inAppendix A.Phillips and Worrell (1913, p. 202)gave the following analysis of gas distillatefrom lignite mined by Cookville Coal and Lumber Company in Titus County:

Yield of gas (cv. ft. /dry ton).... 9,560Illuminants, % 4.6Carbon monoxide, % . 19.4Hydrogen, % . . . 50.4Methane, % 19.4Nitrogen, % 6.2Specific gravity . .537Candle power 3.0B. t. u. /cu. ft. (calc.)........ 558

Cass County. --Lignites crop out in the northern part of Cass County in abelt roughly parallel to Sulphur River (fig. 23). The best known deposits arein the northeastern part of the county, in the vicinity of Alamo and at StoneCoal Bluff along the Sulphur River.

Durable (1892, p. 159) reported two beds of lignite in the vicinity ofAlamo at depths of 49 and 65 feet--an upper seam 1.7 feet thick and a lowerseam 4.1 feet thick but not completely penetrated. At Stone CoalBluff on theSulphur River, Shumard (1859) reported 12 feet of lignite at low-water level.

Wilcox lignites are encountered in wells throughout Cass County, mostlyat depths of 200 to 600 feet. A few thin and lenticular lignite beds are presentin the QueenCityFormation, the formation that forms the surface rock in mostof the county.

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Fig. 22. Distribution ofWilcox GroupinCamp, Frank-lin,andTitus counties,Texas.

Fig. 23. General distri-bution of Wilcox lignites inCass County, Texas. Area ofprincipal deposits ruled.

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Freestone County. --Important andpotentially commercial deposits of lig-nite occur in Freestone County where the entire belt of Wilcox rocks crossesthe county (fig. 24). Less published data are available concerning these lig-nites than those occurring immediately south in Leon County, but inmost re-spects deposits of the two areas appear to be similar.

Manybeds of lignite in Freestone Countyhave burned at the outcrop. Suchburning apparently was the result of spontaneous combustion (Lonsdale andCrawford, 1928).

Severaloutcrops of lignite arepresent in streams andgullies inFreestoneCounty. Individual seams are generally less than 10 feet thick. Dumble (1892)reported three beds of lignite in the northeastern part of the county with themiddle or secondbed 5 feet thick. Lonsdale and Crawford (1928) indicated twoseams, 5 and 12 feet thick, in the southern corner of the county; one sectionshowed a single seam 17 feet thick. Whitcomb (1939a, p. 3) noted a 25-footseam of lignite at a depth of 40 feet ina well 3/4 mile west of Turlington. Thisthickness, cited in several later publications, represents one of the thickestseams of lignite in the State; however, no description was given and the totalthickness may include some other rock in addition to lignite.

Driller's logs of water and oil wells drilled within the Wilcox belt inFreestone County record lignite seams averaging about 6 feet in thickness atdepths ranging from 20 to 300 feet.

Nopast commercial production of lignite isknownfromFreestone County,except for local shaft operations reportedby Lonsdale and Crawford (1928) inthe area west of Donie in the southern part of the county. Much lignite hasbeen producedcommercially from northwesternLeon County immediately southof Freestone County. The best commercial prospects for lignite mining inFreestone County probably are in the southern part of the county.

Analyses of lignites, mostly from Donie, are given in Appendix A.

Gregg County. --A few beds of Wilcox lignite are exposed at low wateralong the Sabine River in the eastern part of Gregg County (fig. 25). As faras is known, however, these lignites are thin and of poor quality. Dumble(1892, p. 169) reported a lignite seam 5 feet thick on the north side of theSabine River in southeasternGregg Countybut noted that the lignite was mostlysandy and impure. In the later 1800's some shafts were sunk along the SabineRiver; the lignite mined was used as fuel by the old Texas, Sabine Valley, andNorthwestern Railroad. No analyses of lignites from Gregg County are avail-able.

Guadalupe County. --Wilcox rocks extend in a southwestern belt acrossGuadalupe County (fig. 26) and though lignite has been reported from theserocks, little is known of its distribution, thickness, and quality. Plummer

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Fig. 24. Generaldistribution ofWilcox lignites inFreestone County, Texas.Area of principal deposits ruled.

Fig. 25. Distribution of Wilcox Group in Gregg County, Texas.

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Fig. 26. Generaldistribution of Wilcox Group inGuadalupe County, Texas.Area of principal lignite deposits ruled.

(1933, p. 575, map, fig. 36) showed five lignite mines in the central andnortheastern part of the county, but there is no mention of these mines inhistext. In describing Wilcox rocks exposed along Cibolo Creek, Deussen (1924,p. 54) noted the presence of lignitic shales but mentioned no lignite deposits.Well-known deposits of lignite occur in Wilcox rocks inBastrop County to thenorth and inexar County to the southwest so that commercial deposits of lig-nite may be present in Guadalupe County. Several logs of water wells givenin the Texas Board of Water Engineers (1937) report on Guadalupe County in-dicate numerous, but relatively thin, beds of lignite in the area of Wilcox out-crop.

No analyses are availableof lignites from Guadalupe County.

Harrison County. --Lignite-bearing rocks are exposed in the easternone-thirdof HarrisonCountyextending ina north-trendingbelt from the SabineRiver to Caddo Lake (fig. 27). Principal exposures occur along the SabineRiver on the Panpla-Harrison County line. Outcrops form shoals in the river,

such as at RockyFord andRobertsonFord (fig. 28). A few outcrops are pres-ent in the northeastern part of the county along the banks of Caddo Lake.

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Fig. 27. DistributionofWilcox lignites inHarri-son County, Texas. Areaofprincipaldeposits ruled.

Fig. 28. Diagram-matic sectionoflignite ex-posed at Robertson Ford,Sabine River, HarrisonCounty, Texas. ModifiedfromDumble(1892,p.164).

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Available analyses of lignites from northeasternHarrison County indicatethat theyare of much the same quality as those farther south in the county, butbeds in the northeastare generally less than 3 feet thick. Those in the southernpart of the county, as exposed along the Sabine River and as mined at Darco,are thicker, averaging 5 to 10 feet.

Lignite-bearing beds in the county have a regional dip to the northwestand dip under younger rocks. Water wells drilled in Marshall and vicinitypenetrated several lignite seams of variable thickness at depths of 30 to 600feet.

Fig. 29. Diagrammatic sections of strip mines at Atlas Chemical Indus-tries, Inc., Darco, Texas, 12 miles southwest of Marshall on State Highway43, Harrison County. A, Section givenby Selvig et al. (1950). B, Section ex-posed in fall of 1961.

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Lignite has beenminedin the vicinity of Darco in south-central HarrisonCounty for several years, and open-pit strip mining by Atlas Powder Companyat the present time represents one of the two current large-scale, lignite-mining operations in Texas (fig. 29). Lignite presently mined at Darco ishauled to Marshall and used in the production of activated carbon. At presentabout 12 feet of lignite, generally in two seams separatedby a thinparting ofclay, is mined. Overburden removed in past operations has ranged from 20 to60 feet. Utilization of lignite in the manufacture of activated carbon has beendescribed by Evans (1944).

Mr. G. H. Scheffler (letter dated May 10, 1961) of Atlas Chemical In-dustries, Inc., has given the following data on lignite mined at Darco:

Proximate analysis

Moisture, % . . . . 33.0Volatile materials, d.b.,%. . . . . . 44.2Fixed carbon, d.b.,%......... 45.1Ash, d.b.,% ................ 10.78.t.u. /lb., d.b. ...........11,200

Ultimate analysis (dry basis)

Carbon, % . . . .. . . 63.9Hydrogen, % . . . . 3.6Nitrogen, %.... 1.0Sulfur, % . 100l o0Ash, % . . . . 10.7Oxygen, % (by difference) 19.8

Ash composition

SiO2, % 35.0R203, % 27.1CaO, % 16.2MgO, %................ 3.0Alkalies, as Na2O, % 1.8

Physical features

Density/cu. ft 77 lb.Weight/acre-foot . ........ .. 1,675 tonsSpecific gravity 1.15 to 1.45, generally

1.20 to 1.25

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Selvig et al. (1950), in a study of the petrography and extractable waxesof American lignites, gave the following data concerning lignites mined atDarco:

Extractable waxes, % (average of two beds)80% Benzene- -20% ethyl

Benzene solution alcohol solutionAs-received basis 1.9 4.1Dry basis . 2.3 5.1Dry basis (ash-free) 2.6 5.7

2/Physical-chemical features of waxes

Waxes extractedbybenzene-ethyl alcohol solution

Melting point, C ............ . . 83 to 87Acid value .................. 58Saponification value 119Ester value . 61Ash, % 0.3Benzene-alcohol solubility 96Ethyl ether solubility . 66

Petrographic components

Anthraxylon, % 31.8Translucent attritus, % 59.5Opaque attritus, %...... 6.9Fusain, % 1.5

Selvig et al. concluded that the lignites of the Darco area are the woodyor xyloid type and contain less extractable waxes than attrital type lignites.

Stadnichenko et al. (1961) listed the following beryllium content in onesample of lignite from Darco:

Average ash content, % 8.9Beryllium content of ash, % 0.0007Beryllium content of lignite, p.p.m 0.6

Standard analyses of representative lignites from Harrison County aregiven in Appendix A.

27For analytical procedure in determining units, refer to Selvig (1950),,

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Henderson County. --Iraportant deposits of Wilcox lignite occur in a beltextending across Henderson County (fig. 30); these deposits underlie, atrelatively shallow depths, most of the central part of the county and have beenthe source of lignite for some of the largest producers in the State. Principalmining was centered in the vicinity of Malakoff where seams 7 to 12 feet thickwere mined. A total of 14 mines havebeen operated, with two mines located6.5 miles northeast of Malakoff, three mines located1.5 miles north of Mala-koff, and seven mines located 25 miles east of Malakoff. Main producers wereAlba-Malakoff Lignite Company and Dallas Lignite Company. Baker (1935)reported lignite seams 6 and 4feet thick from a locality 8 miles west of Athensand up to 12 feet thick in the vicinity of Stockard. Driller's logs of water wellsdrilled in Wilcox rocks of the central part of Henderson County record ligniteat shallow depths in most wells, so that lignites similar to those formerlymined at Malakoff apparently are extensive.

Fig. 30. General distribution of Wilcox lignites in Henderson County,Texas. Area of principal deposits ruled.

Dumble (1892, p. 167) reported lignites along the bluffs of the NechesRiver and at depths of 20 to 40 feet throughout the southeast part of HendersonCounty. These lignites are in the Queen CityFormation and generallyare morelenticular and of much poorer quality than Wilcox lignites. Localdeposits ofcommercial value maybe present.

Analyses of lignites from Henderson County, mostly from Malakoff andvicinity, are given in Appendix A.

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Hopkins County. --Significant deposits of lignite are found inWilcox rocksof Hopkins Countyina belt extending across the southeasternpart of the county(fig. 31). One main seam has an average thickness of about 6 feet; partings ofdark shale, less than 0.5 foot thick, are common. A second seam, minednorthof Como, has a thickness ofabout 8.5 feet. Outcrops are numerous with-in the Wilcox belt.

Fig. 31. Distribution ofWilcox lignitesin Hopkins County, Texas. Area of prin-cipal deposits ruled.

Mining operations, which began in 1901and continued intermittently forseveralyears, centeredat Como inthe southeasternpart of the county (frontis-piece). Stenzel (1948) reportedmining at Como as late as 1946. Twelve mineshave been operated in the vicinity of Como; main operators were Como CoalCompany, Lone Star Lignite Company, and McKay Lignite Mining Company.Seams of lignite 7feetand5. 5 feet thick, at depths of35 to 90 feet, respectively,were mined by these companies. A section of the lignite mined by Como CoalCompanyis shown infigure 32.

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Fig. 32. Section of lignite mined by ComoCoal Company, Como, Texas. From Phillips(1902, p. 15).

Analyses of lignite fromHopkins County aregiven in Appendix A. Phillipsand Worrell (1913, p. 202) gave the following analysis of gas distillate of lig-nite from Hopkins County:

Como Coal Company Lone Star Lignite Company

Gas yield, cv. ft. /dry ton. . . 7,996 9,140Illuminants, % 1081 O8 1.4Carbon monoxide, % 11.8 14.0Hydrogen, % 51.2 55.0Methane, % 20.6 22.2Nitrogen, % ... . .... 1 . 8.0 6.8Specific gravity ........ .457 .373Candle power ... -1.1 -1.0B.t. v. /cv. ft. (calc. ) ..... 518 450

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Phillips (1902, p. 54) reported the following analysis of ash from lignitemined at Como:

Percent

SiOE53.04

A12O3 24.68Fe2O3 7.7CaO 10.59MgO TraceMnO . .. TraceH2SO4 3.53

Lee County.--The mainbelts of Wilcox andJackson lignites occur in LeeCounty, but deposits are scattered and not well known (fig. 33). Lignite cropsout in the southwestern part of the Wilcox lignite belt in the vicinity of YeguaKnobs and Blue Branch; these beds are generally thin, though Dumble (1892)reporteda 6-foot seam at Blue Branch. In the northwestern part of the Wilcoxlignite belt, at Hicks, 4 miles north of Tanglewood, two shafts were operatedduring 1925-1930; lignite was mined from a 4-foot seam at a depth of 50 feet.

Fig. 33. General distribution of lignite deposits in Lee County, Texas.

Area of principal deposits ruled.

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Standard analyses of lignites from Lee County are given in Appendix A.

Phillips and Worrell (1913, p. 202) gave the following analysis of gas distillatefrom Lee County lignites:

Gas yield, cv. ft. /dry ton 5,576Illuminants, %............ 4.8Carbon monoxide, % .. . . . 2Z.6Hydrogen, %............. 41.4Methane, % . . . . . . .. . .. . 23.4Nitrogen, % . . . . . . . .. . . .. 7.0Specific gravity ........... .449Candle power ............ 6.1B.t.u. /cu. ft. (calc. )........ 533

Leon County. --Significant lignite deposits in Leon County occur in theCalvert Bluff Formation, which crops out in the extreme northwestern part ofthe county (fig. 34),, Lignite deposits are in other formations of the county, butthese lignites generally are impure, very thin, and lenticular.

From 1907 to 1930 lignite was mined in the vicinity of Evansville andBear Grass and at times during this period mining was the largest industry ofthe county. Several shafts were operated by two companies- -Houston-LeonCounty Coal Company and Bear Grass Mining Company. Descriptions of thesemines were givenby Stenzel (1939, pp. 229-245).

As reported in mines and in several borings made in the vicinity ofEvansville (Stenzel,1939), the main or mined lignite bed ranges from 7 to 11feet in thickness. Commonly the upper 1 or 2 feet of lignite in this bed is fria-ble and of poor quality resulting in what is generally known as "rotten coal."Shaft depths in the Leon County mines ranged from 30 to 110 feet, and boringsmade in the area just south of Lambs Creek on the old property of Houston-Leon County Coal Company show the main lignite bed at similar depths. Thelignite bed that was mined dips about 1 degree S. 55 E.

Stenzel (1939, p. 245) reported if to 2 million tons of lignite hadbeenmined from the area; an equal amountprobably remains.

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FIG. 34. Distribution of Wilcox lignite deposits inLeon County, Texas.Area of principal deposits ruled.

Standard analyses of lignites from Leon County are given.in Appendix A.Phillips andWorrell (1913, p. 202)listed thefollowinganalyses of gas distillatefrom Leon County lignites:

Bear Grass, Evansville

Gas yield, cv. ft. /dry ton . . . 8,157 9,028 6,500Illuminants, % 1.7 2.1 2.1Carbon monoxide, % 2.6 8.0 11.5Hydrogen, % . .. ....... 49.3 44.2 52.5Methane, % 41.6 31.2 29.4Nitrogen, %..... 5.5 11.6 4.5Specific gravity ,353 .454 .326Candle power.......... -1.1 9.3 1.5B.t.u. /cu. ft. (calc.) 538 549 533

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Limestone County. --Lignite-bearing strata crop out across the south-eastern part of Limestone County, forming the prairie country of that area(fig. 35). Potentiallycommercial deposits areprobably present in the extremeeastern part of the county in the area adjoining Freestone and Leon counties.No published information is available concerning the number and thicknessesof lignite seams in the county, but deposits probably are similar to those inadjacent areas. Available analyses of lignites from Limestone County aregiven in Appendix A.

Fig. 35. Distribution of Wilcox lignite depositsin Limestone County, Texas. Area of principal de-posits ruled.

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Marion County. --Lignite deposits are found in Marion County, but littleis known of their nature, quality, and distribution. Lignite-bearing rocks ofthe Wilcox Group are exposed in the southeastern part of the county and cropout in the banks of the lower part of Cypress Creek and in small streams flow-ing into the north side of Caddo Lake (fig. 36). Most of the lignite beds arethin, with maximum thickness of 15 inches recorded, and probably are not ofcommercial thickness. Well records from the southeastern part of the countyindicate only local and sporadic occurrences of lignite. Thicker and more ex-tensive seams occur at depths of 300 to 400 feet. No development of any of thelignites from Marion County has been reported, and there are no known pub-lished analyses of the lignites.

Fig. 36. Distribution of Wilcox lignite depositsin Marion County, Texas. Area of principal de-posits ruled.

Medina County. --Rocks of the Wilcox Group are exposed in a west-southwest belt across the southern part of Medina County (fig. 37); these arethe only rocks in the county known to contain lignite. Commonly, driller'slogs erroneously indicate lignite or lignitic shale for dark shales in the Cre-taceous Eagle.Ford Formation.

Principal deposits of lignite in Medina County are west of Lytle at theold community of Coal Mine near the junctionof Medina, Bexar, and Atascosacounties. Three mines operated in this area and probably were mining thesame lignite bed as that mined in northwestern Atascosa and southwesternBexar counties. The old Carr mine was situated near the Atascosa Countyline, 1.5 miles west of Lytle; a seam of lignite which averaged 5.5 feet inthickness was mined at a depth of about 60 feet. Three-fourths mile west ofthe Carr mine, Belts Coal Company mined 5 to 8 feet of lignite at a depth of85 feet at its old Riley mine. Just southwest of the Carr and Riley mines,

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FIG- 37. General distribution of WilcoxGroup in Medina County, Texas. Area of prin-cipal lignite deposits ruled.

Bertelli Coal Company mined a seam of lignite averaging 5.5 feet in thicknessat a depth of 50.feet. The lignite at both the Riley and Bertelli mines occurredat a greater depth than that at the Carr mine, and Maxwell (1962) suggestedthat the difference in depth is the result of faulting. All of the mines wereshaft operations. Several analyses of these lignites are given in Appendix A.Logs of the shafts of the Riley and Carr mines are given in figure 38.

Little is known concerning lignites of the Wilcox in the remainder ofMedina County, although it is reasonable to assume that lignites of quality andthickness similar to that formerly mined west of Lytle occur elsewhere in thecounty.

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Fig. 38. Logs of mine shafts west of Lytle, Medina County, Texas. A,Carr mine, 1.5 miles west of Lytle (Dumble, 1892, p. 185). B, Riley mine,2.2 miles west of Lytle (Lonsdale, 1935, p. 20).

Phillips (1902, p. 54) gave the following analysis of ash from lignites ofMedina County:

Carr Mine Bertelli MinePercent Percent

SiO2.......... 63.4 40.46A12O3 ......... 12027 16.92Fe2O3......... 5.95 8.32CaO . o None 15.60MgO.......... Trace 1.22MnO 1.0H2SO4......... 13.71 15.54

The following analyses of gas distillates from lignites of Medina Countywere given by Phillips and Worrell (1913, p. 202):

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Carr Mine Bertelli Mine

Yield of gas, cv. ft. /dry ton .... 6,240 5,358Illuminants, % 2.3 2.1Carbon monoxide, % 11.3 11.2Hydrogen, % . . . 46.2 48.7Methane, % .... . . . 32.7 32.6Nitrogen, %............. 7.5 5.4Specific gravity .423 .40Candle power -1. 4.B.t.v. /cv. ft. (calc.) 550 574

MilamCounty. --Lignite deposits in Milam County are the most importantand most exploited lignites in Texas. At least 34 different companies haveoperated mines in this county during the past 70 years. One of the two large,existing, lignite-mining operations inthe State is conductedbyIndustrial Gener-ating Company southwest of Rockdale.

Lignites in MilamCounty are in the Cal-vert Bluff Formationand extend northeastacross the county to theBrazos River, appar-ently connecting withlignite deposits at Cal-vert Bluff in RobertsonCounty (fig. 39). Sev-eral beds of lignite arepresent but generallyonly two or three areof commercial impor-tance. Individual seamslocallyare up to 20 feetthick but average about7 feet; lignite currentlymined by IndustrialGenerating Companyaverages 13 feet inthickness.

FIG. 39. General distribution of Wilcox lignitedeposits in Milam County, Texas. Area of principaldeposits ruled.

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Mining was centered in the general areas of Rockdale and Milano in thesouthwestern and south-central parts of the county and near Jones Prairie inthe northeast; of these, the Rockdale area was the most important. Mostearlymining in the county was by shafts which were generally sunk to 60 to 100feet (fig. 40), but in recent years mining has been exclusivelyby openpit. Atpresent, Industrial Generating Company is able to strip as much as 150 feetof overburden for as little as 10 feet of lignite (fig. 41).

Mr. G.H. Scheffler of AtlasPowder Company (letter dated May10, 1961) gave the following as atypical analysis of ash from MilamCounty lignites:

PercentSiO2 40.1R203 24.5CaO ............ 13.9MgO 2.7Alkalies, as NaO ... 1.8

Fig. 40. Log of shaft of RockdaleMining Company, near Rockdale, Milam

County, Texas. Modified from Plummer(1933, p. 589).

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Fig. 41. Diagrammatic section of strip mine of Industrial GeneratingCompany, at end of Farm Road 1786, 5 miles south of U.S. Highway 79, south-west of Rockdale, Milam County, Texas.

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Selvig et al. (1950) have given the following data concerning extractablewaxes from lignites taken from the Sandow mine southwest of Rockdale:

Extractable w^xes

As tested, % D.b., % D. b. (ash-free), %

Benzene solution 1.9 2.2 2.665%benzene-35%

ethyl alcoholsolution 3.9 4.4 5.1

80% benzene-20%ethyl alcoholsolution 4.5 5.2 6.0

Physical-chemical features of wax

Waxes extractedbyt benzene-ethyl alcohol solution

Melting point, *C 77 to 81Acid value . . . . 77Saponification value 123Ester value 46Ash, % 0.4Benzene-alcohol solubility 84Ethyl alcohol-ether solubility .... 64Phillips and Worrell (1913, pp. 192-195, 202) gave the following analyses

of residues and gas distillates from Milam County lignites:

Tar (average analysis inpercent)

Waxes extracted bybenzene-ethyl alcohol solution

Residue from lignite, as charged. . . 40.5Residue from dry lignite 56.1Ammoniacal liquor 34.4Total ammonia inraw lignite 0.76Tar, raw lignite 8.1Tar, dry basis 11.2

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Composition of residue (average analysis in percent)

Moisture 0.98Volatile material . . . . . ... . 3.30Fixed carbon. 73.70Ash 22.00Sulfur 1.46B. t.u. /lb . 10,465Free carbon 1.3

Composition of tar distillate (fractions inpercent)

Water . .'....'. 0.40Ist fraction, to 392F, light oil 6.812nd fraction, to 527F, middle oil. ....... 17.953rd fraction, to 600F, heavy oil ........ 28.754th fraction, to66oF, soft paraffin oil . .... 12.00Residue, soft pitch........ 32.57

Composition of cracked pitch (percent)

Hard paraffin .............. 19.01Red products 1.30Coke. 11.00Gas and loss ...... 1.26

Composition of oils from tar distillate

Active phenol, % Bases, % Specific gravity

Ist fraction. . . . 19.51 3.2 0.8302nd fraction. . .. 27.50 6.0 0.9833rd fraction. . . . 20.90 3.0 0.9514th fraction . . . . 24.00 3.0 0.951Hard paraffin . . . 18.00 3.0 0.921

Paraffin in raw tars

Fractions

3rd 4th Hard paraffin/oils

Yield of oils, % 28.75 12.00 19.00Loss by washing, % . . 24.00 27.00 21.00Remainder after washing, % 21.85 8.76 15.00Paraffin content of washed residue, %. . 4.30 12.40 12.50Melting point, C .50 54 59

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Nitrogen content (percent)

Dry lignite 2.53Tar from lignite. 2.82Residue 0.18Gas 4.90

Gas distillate

Gas yield, cv. ft. /dry ton. . 8,842 7,352 9,217 9,755Illuminants,% . 1.8 2.0 0.8 1.8Carbon monoxide, % .... 21.6 19.4 17.9 9.8Hydrogen, %......... 47.8 43.8 46,2 56,2Methane, % . . . . . . . . . 15.9 24.6 20.5 24.4Nitrogen, % 7.7 8.7 5.0 7.4Specific gravity . .503 ,468 .514 ,368Candle power -1. 3. -1. . -1.B.t.u. /cu. ft. (calc. )" " " " 425 485 460 492

Morris County. --Lignites have beenreported from the northern part of MorrisCounty, mostly along the banks of the Sul-phur River and along Whiteoak Creek (fig.42). Little is known of the thickness andquality of these lignites, though probablythey are similar to Wilcox lignites insur-rounding areas. Thin and noncommercialseams of lignite, apparently in the QueenCity Formation, have been reported fromthe vicinity of Daingerfield.

Fig. 42. Distribution of Wil-

cox lignite deposits in MorrisCounty, Texas. Area of princi-pal deposits ruled.

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Nacogdoches County. --Wilcox rocks containing lignites crop out only inthe extreme northwestern and north-central part of Nacogdoches County (fig.43). These lignites represent a continuation of lignites exposed and formerlymined near Timpson and Center in Shelby County to the east. Inother parts ofNacogdoches County, Wilcox lignites are overlain by younger rocks of theClaiborne Group. Extensive deposits of Wilcox lignites in the southernpartof the county are at depths on the order of 500 feet.

Fig. 43. Distribution of Wilcox Group ofNacogdoches County, Texas.

Dumble (1920, p. 279) reported lignite mines on opposite sides of whatis now the Texas and New Orleans branch of the Southern Pacific Railroad,0.5 mile south of Garrison. These mines were operated in 1900 and 1901 bythe East Texas Coal Company and the South Texas Coal Company. Eachmineworked about seven acres of lignite. According to Dumble, the shaft of the

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East Texas Coal Company was 54 feet deep and the mined lignite averaged 4.5feet in thickness. In all, seven operators have mined lignite in the vicinity ofGarrison.

No analyses of lignites from Nacogdoches County have beenpublished.

Panola County. --Surface rocks of most of Panola County belong to theWilcox Group and, accordingly, lignites are found in most of the county.Principal lignite deposits occur in the upper part of the Wilcox Group in thenorthwesternand southwestern parts of the county (fig. 44) 0

Fig. 44. General distribution of lignite de-posits in Panola County, Texas. Area of prin-cipal deposits ruled.

Lignites exposedin the southwestern part of the county, primarily in thevicinity of Gary, are of good quality, but known deposits are thin and generallyless than 3 feet thick. In the northwesternpart of the county, good-quality lig-nites are found in seams as much as 15 feet thick. Lignite deposits of thisarea apparentlyare continuous with those currentlyminedat Darco in southernHarrison County. Excellent exposures occur along the Sabine River and formshoals in the river (figs. 45, 46). Other outcrops of lignite from this part ofthe county have been reported in the vicinity of Tatum and Beckville. Waterwells in northwestern Panola County generally encounter lignites at depthsranging from 15 to 30 feet.

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The only record of lignite mining in Panola County was given by Dumble(1892, p. 192), who reported that several carloads of lignite had been minedfrom a 4.5-foot bed, 4 miles northwest of Beckville.

Analyses of lignites from Panola County are given in Appendix A and in-dicate that some of the best qualitylignites in theState occur in Panola County.

Fig.45. Diagrammatic section of Black Shoals on Sabine River, 1.5 milesupstream from bridge on U. S. Highway 59, Panola County, Texas.

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Fig. 46. Diagrammatic section of shoals on Sabine River, Panola County,Texas. A, One-fourth mile upstream from bridge on State Highway 43. B,Rocky Ford (modified from Dumble, 1892, p. 163).

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Rains County. --Lignite deposits are found in the upper part of the WilcoxGroup"in Rains "County (fig. 47), in the eastern and, especially, southeasternparts of the county. Logs of water wells (Texas Board of Water Engineers,Rains County, 1943) show lignite inbeds 1 to 10 feet thick and at depths of 35

to 200 feet in the extreme southeasternpart of Rains County. Dumble (1892)reported lignite outcrops inbluffs in the eastern part of the countybut was notspecific as to their location.

Although situated very close to the formerly important mining area of

Alba inWood County, no significant mining has been attempted inRains County.The 1909Report of the State Mine Inspector mentioned a commercial operationat Ginger, a community on the Missouri-Kansas-Texas Railroad, 3.5 milessoutheast of Emory. Plummer (1933, p. 599) stated that a lignite mine inRainsCounty, located southwest of Alba near the Sabine River and Wood County line,

was operatedby Morton Salt Company in 1931.

Fig. 47. Distribution of Wilcox lignite deposits inRains County, Texas.Area of principal deposits ruled.

Robertson County. --Significant and important deposits of lignite occur inthe west-central part of Robertson County north of the town of Calvert in thegeneral area of Brazos River, Little Brazos River, and Walnut Creek (fig. 48).Strata containing lignite deposits extend across the county to the northeast inabelt paralleling Farm Road 979; however, lignites in the prairie country of thenortheasternpart of the county generally are thinner and poorer in quality thanthose in the Calvert area. A few lignites occur in the extreme northwesternpart of the county, but these are stratigraphically below the main lignite bedsand are likewise thin and of poor quality. All principal lignites inRobertsonCounty occur in the lower part of the Calvert Bluff Formation.

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Fig. 48. Distribution of lignite depositsinRobertson County, Texas. Area of principaldeposits ruled.

Best exposures of lignite in RobertsonCounty are along the Brazos Riverat Calvert Bluff (fig. 49) in three beds, 12, 3, and 3 feet thick, respectively.Kennedy (1893) reported lignite thicknesses up to 21 feet along Little BrazosRiver and Walnut Creek north of Calvert.

In west-central Robertson County, lignites are found at depths rangingfrom 30 to 400 feet. Beds dip to the southeast so that lignites occur at pro-gressively greater depths in that direction; for example, at Calvert lignitesare at about 250 feet, at Hearne they are at depths of about 400 feet.

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Fig. 49. Diagrammatic section ofCalvert Bluff, east side of Brazos River,2.3 miles downstream fromBlack Bridge on Calvert-Cameron road, RobertsonCounty, Texas.

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Kennedy (1893) reported eleven different seams of lignite in west-centralRobertson County, of which he considered six to be workable.

Small-scale mining bypits, shafts, and small drifts was conducted mostlyin the late1800's and the early 1900's. Most of the mining was done atCalvertBluff on the Brazos River and in the vicinity of Salter, Little Brazos River,and Walnut Creek, a few miles north of Calvert. Phillips (1902, pp, 10, 11)described shaft operations of Central Texas Mining, Manufacturing, and LandCompany, 6 miles northwest of Calvert.

Standard analyses of lignites from Robertson County are given in Appen-dix A.

Rusk County. --Lignites are present in Wilcox rocks which crop out inmost of the eastern half of Rusk County (fig. 50); thin and generally unimportantdeposits of lignite are also reported from the Queen City Formation which isexposedin the westernpart of the county. Dumble (1892) reported an exposureof lignite 3 feet thick, 5 miles northeast of Henderson along Martin Creek. Anearby water well penetrated 6 feet of lignite at a relatively shallow depth.Phillips (1914) noted a bed of lignite 3 to 6 feet thick at Grahams Lake, 12miles west of Henderson; Baker (1935) mentioned two seams of lignite 3.1 feetthick in an area 5 miles southeast of Henderson. Driller's logs of geophysicalshot holes in the adjoining northeasternpart of Cherokee County, reportedbyStenzel (1950), show lignites 2 to 5 feet thick inmost all holes.

Analyses of lignites from Rusk County, given in Appendix A, indicate lig-nites comparable inquality to Wilcox lignites in other areas of northeast Texas,but apparently most are too thin to be ofcommercial importance. Thicker andmore extensive Wilcox lignites occur at greater depths. No known attemptshave beenmade to mine or develop lignites in Rusk County.

Shelby County. --Althoughdeposits of Wilcox lignite are probably extensivein Shelby County, most of them have not been developed (fig. 51). Dumble(1892) reported a seam 4 to 5 feet thick along Attoyac Bayou, 7 miles southof Timpson. Other outcrops are common in the larger streams of the county.Inthe area immediately east of Tirnpson, a seam of lignite 4 to 6 feet thick hasbeen reportedat depths of 55 to 70 feet.

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Fig. 50. Distribution of Wil-cox Group inRusk County, Texas.

Fig. 51. Distri-butionof Wilcox GroupinShelby County, Tex-as.

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The Timpson Coal Company mined lignite just east of the Texas andNew Orleans Railroad, 1.5 miles south of Timpson. Lignite production fromthis mine was intermittent in the early 1900's but apparently was never sig-nificant. Phillips (1902, p8 14) briefly described the mining operation atTimpson, noting that a 6.5-foot seam of lignite was mined at a depth of 25feet, Dumble (1892) reported two shafts sunk on a 5.5-foot seam of lignite inthe southern part of the town of Center; this lignite seam is also found inlocaloutcrops and water wells.

Analyses of lignites from Shelby County are given in Appendix A. Phillipsand Worrell (1913, p. 89) gave the composition of ash from lignite mined atTimpson as follows:

PercentSiO2 25.64A1203 ........... 19.08Fe2O3........... 12.92CaO ..... o .. o . o . 18.68MgO............ 1.76H2SO4........... 20.92

Smith County. --Lignite deposits are common throughout a large part ofSmith County in Wilcox and Queen City rocks (fig. 52). Few, if any, of thenear-surface deposits are ofcommercial value;thebetter grade Wilcox lignites,where present, are at depths generally greater than 500 feet. Surface andnear-surface lignites inSmith County are mostly thin, lenticular, and of poorquality owing to a highcontent ofash and other impurities. No attempt hasbeenmade to develop these lignites on a commercial basis; nevertheless, if carefulexploration is conducted, certain of the deposits may prove to be significant.Dumble (1892, pp. 167-168) indicated lignite seams up to 10 feet in thickness,especially in the northernpart of the county along the Sabine River. Driller'slogs of water and oil wells indicate lignite deposits up to 5 feet thick at depthsof 10 to 300 feet throughout the area indicated in figure 52.

Available analyses of lignites from SmithCounty are given in Appendix A.

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Fig. 52. Distribution of Queen City Formation in Smith County, Texas.

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Uvalde County. --Wilcox lignites occur ina narrow belt extending acrossthe southeastern corner of Uvalde County. Little is known of the quality ofthese lignites; their proximity to deposits in Medina and Zavala countiessuggests they may be similar. Maxwell (1962) reported data from holes drilledabout10 miles southeast of Uvalde (fig. 53) that indicate up to 10 feet of ligniteat depths from 30 to 100 feet. Maxwell also stated that about 2 tons of lignitehad been mined from this area.

No published analyses of lignites from Uvalde County are available.

Fig. 53. Distribution of lignite deposits in Uvalde County, Texas.

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Van Zandt County. --Rocks belonging to the Wilcox Group crop out inabout one-half of Van Zandt County in a belt extending from the southwesternto the northeastern part of the county (fig. 54). Several seams of lignite areexposed at different places in the county, especiallyalong the Sabine River andits tributary streams.

Lignite seams up to 10 feet thick are known from Van Zandt County; how-ever, littlepublished information is available concerning distribution and qual-ity of the lignites., Primarily on the basis of drill-hole data, Perkins andLonsdale (1955) listed south-central Van Zandt County as a general area ofsignificant lignite deposits. In the past, a 10- to 12-foot seam of lignite wasmined about 2 miles northwest of Canton. Phillips et al. (1911, p. 45) gaveanalyses of lignite received from Edgewood Coal and Fuel Company, but it isnot known from what part of the county this lignite was mined.

Fig. 54. Distribution of Wilcox Group in Van Zandt County, Texas. Areaof principal deposits ruled.

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Mr. G.H. Scheffler (letter dated May 10, 1961) gave the following compo-sition of ash from lignite mined in Van Zandt County:

PercentSiO2 43.6R203 . 23.1CaO ... . 1609MgO, . . 2.3Alkalies, as Na2O ....... . " 1.3

Phillips and Worrell (1913, p. 202) recorded the following composition ofgas distillate from Van Zandt County lignite:

Gas yield, cv. ft. /dry ton . . . 6,685Illuminants, % ........... 10Carbon monoxide, % .. . . . . 15.5Hydrogen, % . . . ... . . . . 46.8Methane, % . .... . . . . . 0 . 28.7Nitrogen, % . . . . . . . . . . 7.0Specific gravity........... .465Candle power ............ 2.B. t.u. /cu. ft. (calc. ). . o . . o . . 520

Wood Countyo --Lignite-bearing rocks of the upper part of the WilcoxGroup crop out in the western quarter of Wood County (fig. 55). In the vicinityof Alba where, beginning in 1890, 17 mines were operatedintermittently formany years, three distinct seams of lignite are present. Most of the miningwas done by shaft, with only the uppermost of the three lignite seams mined.As mined, thisbed of lignite ranged inthickness from 8 to 13 feet and occurredat depths of 18 to 40 feet- Stenzel (1948, po 41) noted that lignite was beingmined at Alba as late as 1946.

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Fig. 55. Distribution of lignite deposits in Wood County, Texas. Area ofprincipal deposits ruled.

Rocks of the Wilcox Group generally dip to the east inWood County andare present beneath younger rocks in the central and eastern parts of thecounty. Logs of various wells indicate lignite in the central part of the county.and in the vicinity of Mineola at depths of 300 to 500 feet. These lignites aresimilar to lignites exposed in the western part of the county. Dumble (1892,p. 171) reported "large deposits of brown coal... in the neighborhoodof Haw-kins.... This field is said to cover over a mile of territory, but its actual ex-tent is not known." Surface rocks in this area belong to the Queen City Forma-tion.

Several analyses of lignites from Wood County, mostly of mined lignitesfrom Alba, are given in Appendix A. Analyses of ash from Wood County lig-nites are reported as follows:

North Texas Coal Company (Phillips, 1902, p. 54)

Percent PercentSiO2 33.00 38.73

A1203 . 25.84 23.00Fe2O3 . 7.40 6.00CaO 22.32 24.11MgO.............. TraceMnO TraceH2SO4 11.32 8.51

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Typical analysis of ash from Wood County lignite(Ho G. Scheffler, letter dated May 10, 1961)"

PercentSiO2 o . .. . 45.4R203 00... 23.5CaO 20.4MgO............ 2.8

Zavala County. --Lignites ofpotentialcommercial significance occur onlyin the northwestern part of Zavala County where Wilcox rocks crop out in anarrow belt (fig. 56) O Thin and mostly noncommercial seams of lignite occurin the Bigford Formation throughout much of the remainder of the county.

Fig. 56. Distribution of lignite deposits in ZavalaCounty, Texas.

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Exposures of Wilcox lignites in northern Zavala County, in the vicinityof theNueces River (fig. 57), have been reportedand described by Owen (1889,p. 69), Dumble (1892, p. 188), Vaughan (1900, pp. 61-62), Ashley (1919, p268), Getzendaner (1931, pp. 117-118), Baker (1935, p. 333), and Maxwell(1962). Several seams, up to 10 feet but mostly about 3 feet thick, are presentin the upper part of the Wilcox Group. Baker (1935, p. 351) noted lignite, pre-sumably Wilcox lignite, in a wellat 118 feet, 12 miles west of La Pryor, in-dicating that lignites occur at relatively shallow depths inparts of northernZavala. County.

Fig. 57. Diagrammatic section of lignite exposed on eastbank of NuecesRiver, 1.5 miles downstream from bridge on U.S. Highway 83, Zavala County,Texas. From Maxwell (1962, p. 88).

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Lignite has been mined in Zavala County as indicated by two old mineshafts on thebanks of the NuecesRiver about 1 mile upstream fromthe crossingof U. S. Highway 83. Maxwell (1962) reported that the Missouri Pacific Rail-road Company several years ago mined 10 feet of lignite at depths of 25 to 30feet at this locality. According to Maxwell, one of the shafts may be the oneDumble (1892, p. 188) described from which 4 feet 10 inches of lignite wasmined. Dumble mentioned that lignite from northern Zavala County was usedby blacksmiths at Fto Inge0

Most of the reports of lignite in Zavala County indicate that deposits arehighly lenticular and laterally variable; certain drill holes show no lignite.Evaluation of deposits in this area will require careful test drilling.

Analyses of lignites from Zavala County are given in Appendix A

Miscellaneous Wilcox lignites. --In addition to the counties described,Wilcox rocks also crop out in Cherokee, Dimmit, Falls, Gonzales, Maverick,Navarro, Webb, Williamson, and Wilson counties,, Lignites are reportedfromWilcox rocks of these areas, but as far as is known none of these lignites areof commercial importance.

Yegua Lignites

The Yegua Formation of Texas contains lignite deposits second only inimportance to the lignites of the Wilcox Group. Yegua lignites are not as ex-tensive or as well known as those of the Wilcox and commonly are of slightlypoorer quality. More important deposits of Yegua lignites occur north of theBrazos River, though potentially significant, low-grade deposits are presentlocally in south Texas. In northeast Texas, main deposits of lignites appearto be concentrated in the middle or upper part of the Yegua Formation. Thegeneral outcrop of the lignite-bearing part of the Yegua Formation in Texas isshown in figure 1.

Angelina County. --In Angelina County, lignite occurs in the Yegua For-mation in a belt extending roughly east-west across the central part of thecounty (fig. 58). Rocks within this belt are similar to lignite-bearing rocks inTrinityandHouston counties. Lignites are exposed along banks of the Angelinaand Neches Rivers and are penetratedby most water and oil wells within thegeneralarea of the Yegua outcrop. Principaldeposits appear to be in the upperpart of the formation, primarily in the area from Huntington to Burke. Fromwell data, Dumble (1920, p. 283) reported 12 feet of lignite at depths of 25feet at Huntington and 4 to 7 feet of lignite at depths of 15 feet at Burke.

Atascosa County.--Lignites of the Yegua Formation occur in the south-eastern part of Atascosa County, mostly in the area southwest of Campbellton(fig. 10). These lignites, which are a continuation of the lignites in northernMcMullen County, have been described by Maxwell (1962).

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Fig. 58. Distribution of Yegua Formation in Angelina County. Area ofprincipal lignite deposits ruled.

Maxwell (1962) gave logs of drill holes which indicate 8 to 13 feet of lig-nite along Metate Creek, 3 miles west of Campbellton, and noted that duringexploratory drilling prior to construction of Farm Road 140 bridge at MetateCreek, 12 feet of lignite was encountered between depths of 20 and 30 feet.

Southwest of Metate Creek, along La Parita Creek, Maxwell (1962) re-ported 18 drill holes that showed lignite seams 0.4 to 5.6 feet thick (average 2feet)at depths of 20 to 85 feet (average 35 feet). There are no published analy-ses of Yegua lignites from Atascosa County, but they are probably similar inquality to Yegua lignites in adjacent northeastern McMullen County.

Houston Countyo --One of the few areas in Texas where lignites of theYegua Formation are of known commercial quality and thickness is HoustonCounty. These rocks crop out in a belt extending along the southern margin ofthe county (fig. 59), where lignites are numerous inoutcrops along the TrinityRiver and smaller streams, and in shallow water wells. Lignite beds range inthickness from 2 to 6 feet, averaging about 5 feet, and generally at depths of30 to 60 feet.

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Fig. 59. General distribution of YeguaFormation inHoustonCounty, Texas.Area of principal lignite deposits ruled.

Within the Yegua belt of rocks inHouston County, Dumble (1892) recog-nized two ifaain lignite fields --one in the southeastern part of the county in thearea just east of Piney Creek and representing a continuationof the lignites inTrinity County to the south, and another in the southwesternpart of the county.Lignites of the southwesternfieldare exposed atHydesBluff and WestmorelandBluff on the Trinity River (fig. 60). Dumble reported, from outcrops, lignitethicknesses of 4 to 6 feet in the southeastern field and 2 to 6 feet in the south-western field.

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Fig. 60. Diagrammatic section of lignite exposed at Hydes Bluff, east bankof TrinityRiver, west-northwest of Weldon, southwesternHouston County, Texas.

Fig. 61. Lignite seam mined by Houston County Coal & ManufacturingCompany, Wooters Station, 3 miles north of Lovelady, Houston County, Texas.

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HoustonCounty lignites were mined at Wooters, a railroad siding 3 milesnorthofLovelady, from about 1901 to 1930. During most of this time the mineswere operated by the Houston County Coal & Manufacturing Company. Themined seam of lignite was 5 to 5.7 feet thick (fig. 61) and was reached by a35-foot shaft. Mining operations were describedbriefly by Phillips (1902, pp.11. 14).

Analyses of lignites from Houston County are given in Appendix A.

McMullen County. --Lignites in McMullen County occur in the northernand northeastern parts of the county primarily in the Yegua Formation; a fewlignites are present in the Jackson Group of that area (fig. 62). Maxwell (1962)summarized the occurrence of lignite in McMullen County and reported thick-ness, quality, and distribution of Yegua lignites along San Miguel Creek in the

Fig. 62. General distribution ofYegua lignite deposits in McMullenCounty,Texas. Area of principal deposits ruled.

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general vicinity of the crossing of State Highway 173 From outcrops along

San Miguel Creek, Maxwell reported 7 to 7.5 feet of lignite with less than 20feet of overburden. Fo