luodes-gneiss
TRANSCRIPT
Evaluation of dimension stone in gneissic rocks Ð a case historyfrom southern Finland
H. Luodesa,*, O. Selonenb, K. PaÈaÈkkoÈnena
aGeological Survey of Finland, Regional Of®ce for Mid-Finland, P.O. Box 1237, FIN-70211 Kuopio, FinlandbFinska Stenindustri Ab, FIN-23200 VinkkilaÈ, Finland
Received 13 April 2000; accepted for publication 20 June 2000
Abstract
A dimension stone prospect in southern central Finland was assessed by a detailed mapping, geo-radar survey, and core
drilling. The prospect is a veined and bedded garnet±cordierite gneiss, consisting of a dark schistose medium-grained
palaeosome and a light coarse-grained granitic leucosome. Both components are found mainly as thin units, but the leucosome
can occur as individual veins several metres thick, which leads to disturbing variations in the appearance of the stone. The
soundness of the stone is de®ned by the amount of tight, but open cracks in the palaeosome and weakness zones in the
weathered leucosome. As a whole, the soundness is diminished down to 10 m below the outcrop surface. Furthermore, a
subhorizontal body of younger granite is identi®ed at approx. 8±20 m depth. Consequently, the prospect is not feasible for
production of dimension stone.
The core drilling was decisive in the ®nal evaluation of the prospect because the true density of the cracks and the subsurface
granite were identi®ed by the method. Only with the use of core drilling could the proper interpretation of the characteristics of
the prospect be made, demonstrating the importance of three-dimensional investigation of a dimension stone prospect. q 2000
Elsevier Science B.V. All rights reserved.
Keywords: Dimension stone; Building stone; Gneiss; Granite; Finland
1. Introduction
Dimension stone is a natural rock that satis®es
given qualitative requirements and is hence quarried
and processed into de®nite shapes and sizes. Rock
types used as dimension stone include, e.g. granite,
gneiss, gabbro, diabase, marble, limestone, sandstone,
soapstone, and slate. Dimension stone is mainly
utilized in the building, construction, monument and
tombstone industries. The de®nition of dimension
stone covers rough blocks and ®nished material, but
excludes crushed or powdered stone consumed as an
aggregate or reconstituted to form arti®cial stone (see,
e.g. Allison (1984) and Niini (1986)).
Dimension stone is used in areas where the aesthe-
tical properties of stone are crucial. A special feature
in the commerce of dimension stone is its dependence
on fashion. The popularity of stone types changes like
that of clothing, and the anticipation of coming
changes is often almost impossible. The appearance
of a stone is thus a very important criterion for good
dimension stone. Even if stone is a product of nature,
the quality requirements concerning the colour of the
Engineering Geology 52 (2000) 209±223
0013-7952/00/$ - see front matter q 2000 Elsevier Science B.V. All rights reserved.
PII: S0013-7952(00)00059-4
www.elsevier.nl/locate/enggeo
* Corresponding author.
E-mail addresses: hannu.luodes@gsf.® (H. Luodes),
olavi.selonen@®nskastone.® (O. Selonen),
kari.paakkonen@gsf.® (K. PaÈaÈkkoÈnen).
stone are very strict. The colour should be as uniform
as possible across the entire deposit. If the stone is
classi®ed as a one-coloured type, stripes, inclusions,
or veins of a differing colour cannot be accepted in a
stone of the ®rst class. However, if the stone is classi®ed
as a multicoloured type, an appropriate variation of the
colours is required, but also in this case the colour and
design of the stone must be homogeneous enough so
that the market can identify it as one and the same
product. The second crucial criterion for feasible
dimension stone is the soundness of the deposit. The
soundness is de®ned by the use of the stone and by the
demands of the processing industry. For example, a
suitable size of the production blocks for the modern
gang saws varies from approx. 2:40±2:90 £1:30±1:90±0:70±1:40 m; which means that the
spacing of the fracturing in the deposit must be at
least 2±3 m. The third important criterion for good
dimension stone deposit is the market demand for a
stone type. Even if the appearance and soundness are
at an acceptable level, the stone has no value without
demand from the market, which is again dependent
upon the ever-changing fashion. Other criteria for a
feasible dimension stone deposit include infrastruc-
tural and technical criteria. The location of the deposit
is essential for its long-term utilization. It should not
H. Luodes et al. / Engineering Geology 52 (2000) 209±223210
Fig. 1. Geological map of southern Finland. The location of the study area is indicated. Modi®ed after Simonen (1980).
be located near sensitive nature areas or objects, but
ought to be situated close to good transport facilities.
When stone is used by the construction and building
industry, it must satisfy strict physical and mechanical
requirements. These properties are measured in certi-
®ed laboratories by standardized methods. For the
quality demands of dimension stone, see Harben and
Prudy (1991), Jefferson (1993), Shadmon (1996),
Selonen (1998), and Selonen et al. (2000).
Geological investigations of dimension stone
deposits have two goals: identi®cation of ªnewº
deposits and development of ªoldº deposits/quarries
(see, e.g. Ribeiro et al., 1999; Taboada et al., 1999;
Perdahl, 2000; Selonen et al., 2000). A new deposit is
often localized through a stepwise regional explora-
tion survey where the identi®cation of a prospect with
potential for dimension stone is made by a desk study
and a ®eld mapping (Selonen et al., 2000). If the
prospect is interesting enough, detailed mapping,
geo-radar survey, core drilling, test production, test
processing, and commercial testing are available for
further assessment (Selonen et al., 2000). Some of
these methods, such as geo-radar survey or core
drilling, can be used, e.g. when developing an opera-
tional quarry (Selonen et al., 2000).
We have discussed earlier dimension stone evalua-
tion on a regional scale (Selonen et al., 2000) Ð in
this paper we shall describe a case history of a
prospect-scale assessment and discuss the applicabil-
ity of the different investigation methods.
2. Study area
The prospect is a garnet±cordierite gneiss located
in southern central Finland (Fig. 1) within an area
of highly deformed and metamorphosed rocks of
the Palaeoproterozoic age. The prospect was iden-
ti®ed by a regional exploration study and it was
primarily evaluated by a ®eld mapping during
which the general soundness and appearance of
the stone were de®ned. This preliminary assessment
indicated that the prospect had potential enough for a
detailed investigation as the appearance of the veined
gneiss was very interesting, and because there is a
market for such stone. Furthermore, on the exposed
outcrops the stone appeared to be relatively sound.
The location of the prospect with respect to roads,
nature objects, and houses is also suitable as it is
situated by a good forest road and because the nearest
house is at a distance of 500 m. The prospect,
which is a rounded hill with a relative elevation
of approx. 20 m, measures approx. 200 £ 250 m
(Fig. 2) and is well-exposed or covered only by
a thin layer of soil except for the eastern and
south-eastern parts.
On the basis of the ®eld mapping, a research plan
was designed, including detailed mapping, geo-radar
survey, core drilling, reserve assessment, test quarry-
ing, test processing, and quarry planning.
3. Methods of investigation
The site investigations commenced with topogra-
phical measurements by tachymeter and with the
planning of mapping traverses. The total length of
the 3±5 m wide traverses was approx. 820 m (Fig.
2). The exposures in the traverses were cleaned by
compressed air and pressurized water jets.
After cleaning and washing, the traverses were
measured and mapped in detail on a scale of 1:100.
During the detailed mapping, special attention was
paid to the composition, colour, and structure of the
stone, as well as the fracturing. A couple of block
samples were extracted, and a total of 60 specimens
were collected along the traverses by a hand-held
diamond drill. The specimens were split and polished
for examination of colour and mineral composition.
Important portions of the traverses were also photo-
graphed.
The subsurface fracturing along the traverses was
investigated by ground penetrating radar (geo-radar),
using antennae of 100 MHz and 400 MHz. The depth
penetration was 20±25 m, and the total lateral length
of the geo-radar pro®les was approx. 800 m. The geo-
radar pro®les were interpreted in order to study the
overall soundness of the prospect.
A total of 11 core drill holes were drilled (Fig. 2),
adding up to approx. 232 m of drill core (approx.
40 mm in diameter). The soundness and the variations
in the composition of the stone were special targets in
studying the drill cores.
Because of the poor production properties of the
prospect, the reserve assessment, test quarrying, test
processing, and quarry planning were later omitted.
H. Luodes et al. / Engineering Geology 52 (2000) 209±223 211
H. Luodes et al. / Engineering Geology 52 (2000) 209±223212
Fig
.2
.T
op
og
rap
hy,
map
pin
gtr
aver
ses,
geo
-rad
artr
aver
ses,
and
loca
tion
of
the
dri
llhole
sin
the
pro
spec
tar
ea.
4. Evaluation of the prospect
4.1. Appearance of the stone
The migmatitic and veined garnet±cordierite gneiss
is composed of a dark gneissic palaeosome and a light
granitic leucosome (Fig. 3A). The main minerals in
the palaeosome are plagioclase, potassium feldspar,
quartz, cordierite, garnet, and mica, whereas the
leucosome consists of potassium feldspar, plagio-
clase, quartz, and garnet.
The schistose and bedded palaeosome consists of
pelitic and psammitic layers, the pelitic layers typi-
cally including granitic veins, while the psammitic
layers are more homogeneously gneissic in composi-
tion. The colour of the medium-grained pelitic
palaeosome is dark grey. The slightly folded
schistosity strikes N308E and dips approx. 608SE.
The bedding is de®ned by dark grey and ®ne-grained
psammitic layers (Fig. 3B) parallel to the schistosity.
The thickness of the beds is mostly less than 50 cm,
but occasionally can be up to 7 m thick. They occur
randomly in the prospect area (Fig. 4), and the spacing
is commonly tens of metres and rarely 30±50 cm.
The anatectic and granitic leucosome veins are
massive and medium or coarse-grained, striking
parallel or obliquely to the schistosity and bedding.
They occur as narrow veins, a few centimetres wide,
and as individual layers with a thickness of up to 6 m
(Fig. 3C). The contact between the thick leucosome
layers and the veined gneiss is often sharp. The
spacing of the randomly occurring individual
leucosome veins is mostly in the order of several
metres (Fig. 4). The colour of the leucosome is mainly
light grey or yellowish, but brownish and reddish
zones occur within the veins.
In the middle of the prospect area there are small
intrusions of a younger, red, and coarse-grained
granite (Fig. 4), clearly differing in appearance from
the leucosome. The granite is found in a couple of
H. Luodes et al. / Engineering Geology 52 (2000) 209±223 213
A
Fig. 3. (A) Garnet±cordierite gneiss typical for the prospect area. (B) Bedding in the garnet±cordierite gneiss. (C) Modes of occurrence for the
leucosome in the garnet±cordierite gneiss. (D) Non-penetrative cracks in the garnet±cordierite gneiss. The cracks are often con®ned to the
layers with psammitic material. The length of the compass is 12 cm.
exposures on the outcrop surface and as a 2±5 m thick
subhorizontal lens approx. 8±20 m beneath the
surface.
4.2. Soundness of the stone
The garnet±cordierite gneiss is typically fractured
by discontinuous (some tens of centimetres long),
non-penetrative, tight, almost closed cracks, which
strike perpendicularly (N608W) or diagonally
(N758E and N158W) to the schistosity (Fig. 3D).
The dip of the cracks is normally either subvertical
or subhorizontal. The fracture surfaces are brownish and
ªrustyº. The density of the cracks varies considerably
because of their tendency to occur in clusters, but in
general the fracturing is denser when the material
becomes more psammitic and less granitic.
The fractures in the leucosome are open and strike
N308E, parallel to the schistosity. The open fractures
typically thicken into zones where the stone is
brownish with a structure weakened by strong
weathering. In the separate leucosome veins, these
zones can be up to a couple of metres wide.
Commonly, the weathering reaches down to 10 m
below the surface, but some weathered zones are
found even at 20 m depth. The open fractures occa-
sionally occur in the palaeosome. Clustering of the
fractures is typical (Fig. 5).
The subsurface fracturing (except for drill holes 8
and 6, Fig. 2) is dense in the ®rst 5 m below the
outcrop surface throughout the prospect area, with a
spacing seldom exceeding 1 m. In the western parts of
the prospect (drill hole 7, Fig. 2), the portion of dense
fracturing reaches down to 11 m.
The site is bordered by late shear/fracture zones
approx. parallel to the schistosity in the western
(strike of N258W) and south-eastern (strike of
N158E) parts. The colour of the stone is often reddish
in these zones.
4.3. Feasibility of the prospect
In the international market for dimension stone the
garnet±cordierite gneiss of this study is classi®ed as a
H. Luodes et al. / Engineering Geology 52 (2000) 209±223214
B
Fig. 3. (continued)
multicoloured stone type, which is very sought after.
The product is de®ned by the appearance of the
contrasting narrow veins of dark grey gneissic
palaeosome and light grey/yellowish granitic
leucosome, forming a relatively regular design. The
appearance is further enhanced by a vivid weft of
clusters of red garnet and occasional blue cordierite.
Within the de®nition of the product, the leucosome
can occur as narrow separate veins cutting the main
schistosity.
The several metres thick leucosome layers will
pose a problem as they form an unacceptable variation
in the appearance of the product. In some cases there
could be blocks, which would almost entirely consist
of the light granitic material. The occurrence of the
leucosome as separate layers also indicates that, due
to the mineralogical differences, the sharp contact
between the leucosome and veined gneiss is a prob-
able zone of weakness along which the stone easily
breaks. The rust-brown colour of the weathered zones
in the leucosome is another defect in the appearance
of the stone, which diminishes the value of the
prospect.
In spite of the dif®culties described above, the
appearance of the stone is basically very interesting
and its defects do not destroy the production possibi-
lities of the prospect. The real problem is the lack of
soundness of the stone. As the garnet±cordierite
gneiss is composed of units with different grain size,
mineral composition, and thickness, the fracturing
varies accordingly and no regular joint system (e.g.
cubic) can be found. The total soundness of the stone
is determined by the amount of cracks and by the
weathering of leucosome. In general, the fracturing
is denser in the ®ne-grained layers than in the
coarse-grained layers and the cracks are especially
well-developed in the psammitic layers. Except for
the northern parts of the prospect area, the fracturing
is dense within 5 m below the outcrop surface, and in
the west the dense fracturing reaches even deeper. The
leucosome is often weathered down to 10 m, indicat-
ing that the physical and chemical weathering has
H. Luodes et al. / Engineering Geology 52 (2000) 209±223 215
C
Fig. 3. (continued)
advanced more easily in the coarse-grained granitic
material than in the less porous palaeosome. The
combined effect of the cracks and the weathering of
the leucosome is that the soundness of the stone is
diminished 10 m down from the outcrop surface,
meaning that the recovery rate of the extraction will
be very low during the ®rst two quarry layers. Below
this, the stone will be more sound, but there, the
several metres thick granitic intrusion will lower the
pro®tability of the extraction. Several thousands of
cubic metres (three production layers) would have to
be quarried with a very low output before stone of
reasonable quality is reached. In consequence, the
costs of founding a quarry would be too high to
make it pro®table.
The facts presented above show that the prospect is
not suitable for production of dimension stone.
5. Remarks on the individual evaluation steps
The evaluation described above is based upon a
combination of results from all the applied investiga-
tion methods, while in this section we discuss some of
the issues and problems connected to the individual
methods and evaluation steps during the assessment.
As the prospect was not thickly covered by vegeta-
tion and trees, it was possible to prepare the mapping
traverses almost to the planned length. Only in the
eastern and south-eastern parts, due to the thick soil
cover, did the traverses become shorter than desired.
The detailed mapping in this case was better suited for
assessment of the appearance of the stone than the
soundness of it. The palaesomes and leucosomes
had a relatively consistent and easily mappable strike
without considerable variations. Furthermore, the
main defects, the psammitic layers and the thick
leucosome veins, were easy to observe as their
appearance deviated notably from that of the veined
gneiss. By contrast, the evaluation of the soundness
was problematic due to the absence of a distinct joint
system. The attitude of the discontinuous and almost
closed cracks as well as the degree of weathering of
the leucosome were hard to interpret from the outcrop
H. Luodes et al. / Engineering Geology 52 (2000) 209±223216
D
Fig. 3. (continued)
H. Luodes et al. / Engineering Geology 52 (2000) 209±223 217
Fig
.4.
Geo
logic
alfe
ature
sof
the
pro
spec
tas
obse
rved
inth
etr
aver
ses.
H. Luodes et al. / Engineering Geology 52 (2000) 209±223218
Fig
.5
.S
oun
dn
ess
of
the
pro
spec
tas
mea
sure
din
the
trav
erse
s.T
he
non-p
enet
rati
ve
crac
ks
are
om
itte
dbec
ause
of
thei
rsm
all
size
.
surface, leading to an uncertain assessment of the
amount of fracturing. While mapping the prospect,
only indications of the younger granite were observed,
and no knowledge of its shape could be obtained
because of the low relief of the study area.
The geo-radar survey in this study was done only
along the cleaned traverses. Except for the western
parts of the prospect, no distinct horizontal fracture
surfaces were identi®ed in the geo-radar pro®les,
agreeing with the observation of the absence of a
major joint system. However, features indicating
exfoliation connected to the weathering of the upper
layers were occasionally observed (Fig. 6). The
weathered zones of weakness and the clusters of the
open and tight fractures were saturated with water,
giving good radar re¯ections, whereas the individual
cracks seldom appeared in the pro®les. Features that
could represent tilted large-scale fractures were
observed occasionally (Fig. 6), but we were not able
to con®rm these features by the core drilling. No sign
of the younger granite body was obtained in the geo-
radar survey although it could have been possible
considering the penetration depth of the radar signal.
Apparently, the dielectric properties of the granite did
not differ enough from those of the garnet±cordierite
gneiss to give a clear re¯ection at their contact.
Furthermore, the contact was sharp and unweathered,
offering no surface for re¯ections.
The core drilling was focused on the study of the
soundness of the stone, especially on the aspects that
H. Luodes et al. / Engineering Geology 52 (2000) 209±223 219
Fig. 6. Thirty metres of interpreted geo-radar pro®le. Tilted large-scale fractures are enhanced with lines. Weathering of the outcrop surface can
be seen down to 3 m depth.
H. Luodes et al. / Engineering Geology 52 (2000) 209±223220
could not be exactly veri®ed by the detailed mapping
and the geo-radar survey: the density and depth
dimension of the small-scale cracks and the degree
and depth of the weathering of the leucosome. In
drill core, all the individual cracks (also the semi-
closed cracks) opened, thus de®ning the real density
of fractures (Fig. 7). Furthermore, the variation of the
intensity of the fracturing in the different layers with
different composition appeared well in the drill core.
The weathering of the leucosome was indicated by
loss of core, i.e. parts of the core where the stone
had totally disintegrated during drilling (Fig. 7).
Other important factors that could be con®rmed by
the core drilling included the absence of a distinct
joint system, the consistent migmatitic structure of
the stone, and the occurrence of the leucosome also
as separate veins with sharp contacts to the veined
gneiss. Only with the help of the core drilling could
the subsurface subhorizontal lens of younger granite
be identi®ed (Fig. 7), which was the decisive factor
in our evaluation of the prospect as being non-
economical.
6. Discussion
The investigation methods used in this case are
standard in geological ®eldwork. In dimension stone
evaluations their purpose is to provide the facts
needed for a decision to open a quarry or to abandon
the site. Hence, the assessment of a dimension stone
prospect is targeted to investigate its production
properties, i.e. the effects of the geological character-
istics on extracting, processing, and utilizing the
stone as building material. In most cases, reserves of
stone homogeneous and sound enough for at least 10
years' production should be secured. This emphasizes
the need for three-dimensional consideration of the
dimension stone prospects by utilizing the appropriate
methods.
The case presented in this paper is a good example
of the importance of the use of subsurface investiga-
tion methods, especially core drilling. While all the
previous evaluation steps were necessary to provide a
full understanding of the prospect and to reach the
conclusion that the prospect was not suitable for
dimension stone production, the results from the
core drilling were fundamental for the ®nal assess-
ment. After the detailed mapping, the prospect
appeared to be more sound than it was in reality. It
is typical that the true nature of the fracturing is very
dif®cult to judge exactly from the outcrop surface.
Commonly, a zone of intense fracturing is restricted
to the surface of the rock, and underneath is a
discontinuity, usually a distinct horizontal fracture
below which the fracturing diminishes substantially.
Therefore, the uppermost layer of the bedrock, i.e. the
®rst production layer, is often largely useless as
dimension stone. If there is any vertical exposure or
local relief, some models of the fracturing on the
outcrop surface can be gained by carefully examining
the precipices. If a deep enough vertical cross section
is not available, as in this case, the data gathered by
the detailed mapping should not be extrapolated
downwards below the exposed surface without further
controls by radar or drilling.
The appearance of the stone in this case could be
assessed quite well by the detailed mapping because
the outcrop surface was relatively fresh. However, it
must be pointed out that weathering, a process
enhanced in the humid/tropical regions, but active
also in the temperate/polar areas, is another important
feature that has a considerable effect on the reliability
of the detailed mapping. Depending upon the stone
type and the thickness of the soil cover, the weathering
can affect the surface of the rock from a few centimetres
down to a few metres depth. For example, the true
colour of a stone does not come out on the weathered
surface and small drilled samples or block samples
must be taken. Sometimes even shallow core drilling
(from 5 to 10 m deep) is needed to penetrate the
weathered zone. But, for example, due to the different
weathering rates of minerals, the heterogeneity in the
structure of the stone is intensi®ed and can well be
observed on the weathered surface.
The subsurface methods used in this study included
geo-radar survey and core drilling. The results of the
geo-radar survey indicated a fair general soundness,
giving the impression of a feasible prospect. But, as
the fracturing of the prospect was mainly in the form
H. Luodes et al. / Engineering Geology 52 (2000) 209±223 221
Fig. 7. Logged drill cores. Note the occurrence of the granite. For location of the drill holes see Fig. 2. Not to lateral scale.
of small and almost closed cracks, the ®nal soundness
could not be determined by the geo-radar survey; the
dry individual cracks did not show up well in the radar
pro®les. In general, the advantage with a geo-radar
survey is that it gives a large cross section of the
subsurface fracturing. In planning for dimension
stone production, the knowledge of the spacing and
dip of the major subsurface horizontal and sub-
horizontal fractures is essential for the estimation of
the production levels and the block sizes. The geo-
radar survey is nevertheless a more feasible method in
homogeneous rock types than in heterogeneous types.
In the latter case, the proper interpretation of the
results is more dif®cult as different internal structures
of the stone are often seen in the radar pro®les. If the
material is strongly deformed and folded, these
structures can be falsely interpreted as fractures, see
also HaÈnninen et al. (1991) and HaÈnninen (1992).
Compared to the geo-radar survey, the core drilling
gives very local information but the bene®t is that it
produces an actual sample of stone in which both the
fractures and the appearance can be studied. Selected
parts of the core are split and polished in order to
increase the reliability of the assessment of the
appearance. There are some geological features that
can only be observed in drill core. For example, as
demonstrated by this case, the small-scale cracks
often open only during drilling. Another example is
mineralogical weaknesses such as thin mica stripes,
barely visible to the eye, affecting the durability of
stone. A problem with core drilling is, however, that
a dimension stone prospect cannot be drilled as
densely as an ore body because the drill holes can
spoil otherwise suitable stone, emphasizing the need
for a careful planning of the drilling. In this case, the
core drilling proved to be the most ef®cient subsurface
method as it revealed the real soundness of the
prospect and the existence of the younger granite
below. By drilling we were able to construct the
®nal three-dimensional view of the prospect, best
exempli®ed by the discovery of the granite.
Although expensive, core drilling was the method
that showed that a quarry at this site would not
have been pro®table.
A prospect evaluation, like the one described in this
paper, can falsely be regarded as a series of operations
executed in a certain order to mechanically evaluate
the prospect. In all cases, however, a proper under-
standing and interpretation of geological phenomena
rising from the knowledge of the local geology
combined with the investigation operations give the
best result. We conclude that for a successful evalua-
tion study, the discontinuous and varied nature of
geological features in three dimensions must be
clearly understood.
Acknowledgements
This work was ®nancially supported by Finska
Stenindustri Ab and the Geological Survey of Finland,
which is gratefully acknowledged. Mr Pentti
Toivanen, Mr Erkki Niskanen, and Mr Hannu Repo
(Geological Survey of Finland) assisted in the ®eld
work, Mr Pekka MaÈaÈttaÈnen (Geological Survey of
Finland) was responsible for the topographical
measurements and Mr Jukka Leino (Geological
Survey of Finland) for the geo-radar survey. Mr Veli
Juhani HaÈnninen (Finska Stenindustri Ab) took the
block samples. Mr Ream C. Barclay (AÊ bo Akademi
University) corrected the English language. Dr I.W.
Farmer and an anonymous reviewer critically evaluated
the manuscript. Their contributions are highly appre-
ciated. Prof. Carl Ehlers (AÊ bo Akademi University,
Department of Geology and Mineralogy) is thanked
for his constructive comments on the manuscript and
for the use of the infrastructure of the department.
References
Allison, P., 1984. Dimension stone Ð a rock steady market. Ind.
Miner. 202, 19±35.
HaÈnninen, P., 1992. Application of ground penetrating radar and
radio wave moisture probe techniques to peatland investiga-
tions. Geol. Surv. Finland Bull. 361, 71pp.
HaÈnninen, P., PaÈaÈkkoÈnen, K., Tervo, T., 1991. Geo-radar in dimen-
sion stone explorations. Geol. Surv. Finland Spec. Pap. 12, pp.
117±118.
Harben, P., Prudy, J., 1991. Dimension stone evaluation. From
cradle to gravestone. Ind. Miner. 281, 47±61.
Jefferson, D.P., 1993. Building stone: the geological dimension.
Quat. J. Engng Geol. 26, 305±319.
Niini, H., 1986. Classi®cation and development of bedrock
resources in Finland. Bull. Geol. Soc. Finland 58, 335±350.
Perdahl, J.-A., 2000. Prospecting of dimension stone in glaciated
terrain. Roc Maquina (March), 108±109.
Ribeiro, J., Saraiva, J., Sousa, A.J., Pereira, H.G., Taboada, J., 1999.
Contribution to ªin situº quality evaluation of ornamental
granite. Roc Maquina (March), 79±84.
H. Luodes et al. / Engineering Geology 52 (2000) 209±223222
Selonen, O., 1998. Exploration for dimension stone Ð geological
aspects. Academic dissertation. AÊ bo Akademi University.
Department of Geology and Gineralogy. Turku, Finland, 64pp.
Selonen, O., Luodes, H., Ehlers, C., 2000. Exploration for dimen-
sional stone - implications and examples from the Precambrian
of southern Finland. Engng Geol. 56 (3/4), 275±291.
Shadmon, A., 1996. Stone: An Introduction. 2 Intermediate
Technology Publications, London (172pp.).
Simonen, A., 1980. The Precambrian in Finland. Geol. Surv.
Finland Bull. 304, 58pp.
Taboada, J., Vaamonde, A., Saavedra, A., 1999. Evaluation of the
quality of a granite quarry. Engng Geol. 53, 1±11.
H. Luodes et al. / Engineering Geology 52 (2000) 209±223 223