naturally occurring - materials synthesized in laboratory do not count, must be formed by natural processes in wild

inorganic - not formed by organic chemistry (e.g., sugars, etc.)

homogeneous solid - single substance in solid phase which cannot be physically separated into simpler compounds

definite chemical composition - composition can be represented as chemical formula (e.g., NaCl), although variation in exact composition is possible (e.g., (Mg, Fe)2SiO4 ) [range in color, hardness, specific gravity]

ordered atomic arrangement – repeating structure at the atomic level, which expresses as symmetry in large specimens, i.e., crystalline structure.

http://www.uoregon.edu/~jrice/geol311

Mineral - A naturally occurring, inorganic, homogeneous solid with a definite chemical composition and an ordered atomic arrangement.

Mineral Properties

Crystal Form• Cleavage/

Fracture• Color• Streak Color• Luster

Crystal Form• Cleavage/

Fracture• Color• Streak Color• Luster

• Hardness• Tenacity• Specific Gravity• Acid Test• Magnetism

• Hardness• Tenacity• Specific Gravity• Acid Test• Magnetism

Crystal symmetry is controlled by the atomic structure of mineral

Mineral Properties

• Crystal Form• Cleavage/

Fracture

Color• Streak Color• Luster

• Crystal Form• Cleavage/

Fracture

Color• Streak Color• Luster

• Hardness• Tenacity• Specific Gravity• Acid Test• Magnetism

• Hardness• Tenacity• Specific Gravity• Acid Test• Magnetism

Characteristic for some minerals, useless for most

QuartzSiO2

Hardness = 7

Rose QuartzRose Quartz

SmokeyQuartz

QuartzCitrine

AmethystAmethyst

Carnelian

OnyxJasper

Mineral Properties

• Crystal Form• Cleavage/

Fracture• Color

Streak Color• Luster

• Crystal Form• Cleavage/

Fracture• Color

Streak Color• Luster

• Hardness• Tenacity• Specific Gravity• Acid Test• Magnetism

• Hardness• Tenacity• Specific Gravity• Acid Test• Magnetism

Streak Color - Color of powdered mineral, which may or may not be the color of the crystal

Streak: Color of powdered mineral on porcelain plate

Hardness ~ 6.5Good for metallic opaque minerals,

Not good for silicates, transluscent/transparent minerals, and minerals harder than the streak plate (color of streak plate)

Pyrite Hematite

• Crystal Form• Cleavage/

Fracture• Color• Streak• Luster

• Crystal Form• Cleavage/

Fracture• Color• Streak• Luster

• Hardness• Tenacity

Specific Gravity• Acid Test• Magnetism

• Hardness• Tenacity

Specific Gravity• Acid Test• Magnetism

Specific Gravity - density of the material (g/cm3)

Mineral Properties

Specific Gravity

Related to both the atomic weight of the contained elements, and how tightly the atoms are packed

Orthorhombic CarbonatesAll minerals have same structure, only cation differs

Mineral Formula Cation g/cm3

Aragonite CaCO3 20 2.95

Strontianite SrCO3 38 3.76

Witherite BaCO3 56 4.29

Cerrusite PbCO3 82 6.55

Mineral Properties

• Crystal Form• Cleavage/

Fracture• Color• Streak Color

Luster

• Crystal Form• Cleavage/

Fracture• Color• Streak Color

Luster

• Hardness• Tenacity• Specific Gravity• Acid Test• Magnetism

• Hardness• Tenacity• Specific Gravity• Acid Test• Magnetism

Luster - quality of light reflected from mineral surface

Luster - quality of light reflected from mineral surface

metallicpyrite

gold

silver

Luster quality of light reflected from mineral surface

resinouspearly

vitreous (glassy)non-metallicSome minerals may be listed in both metallic and non-metallic, or in the incorrect table, i.e., limonite

Mineral Properties

• Crystal Form• Cleavage/

Fracture• Color• Streak Color• Luster

• Crystal Form• Cleavage/

Fracture• Color• Streak Color• Luster

Hardness• Tenacity• Specific Gravity• Acid Test• Magnetism

Hardness• Tenacity• Specific Gravity• Acid Test• Magnetism

Hardness - resistance of mineral to scratching or abrasion

Hardness: resistance to scratchingCompare with other objects or other mineral of known hardness. Some

minerals can have a varying hardness due to impurities

Glass Plate (H = 5.5), very good test.

Fig. 02.14

Muscovite

Hardness < 2

Can scratch with fingernail (H=2.5)

Muscovite

Hardness < 2

Can scratch with fingernail (H=2.5)

Fig. 02.15c

Fluorite

Hardness =4

Can scratch copper penny (H=3.5), but not glass plate (H=5.5)

Fluorite

Hardness =4

Can scratch copper penny (H=3.5), but not glass plate (H=5.5)

Fig. 02.15a

Quartz

Hardness =7

Scratches glass plate (H=5.5). Hardest of common minerals

Quartz

Hardness =7

Scratches glass plate (H=5.5). Hardest of common minerals

Mineral Properties

• Crystal Form• Cleavage/

Fracture• Color• Streak• Luster

• Crystal Form• Cleavage/

Fracture• Color• Streak• Luster

• Hardness• Tenacity• Specific Gravity

Acid Test• Magnetism

• Hardness• Tenacity• Specific Gravity

Acid Test• Magnetism

Reaction to dilute acid; especially useful in identifying carbonate minerals

Minerals like calcite react with weak acid, dissolving the mineral and producing lots of bubbles (effervescence)

Calcite: CaCO3

HCl + CaCO3 > H2O + Cl- + Ca+ + CO2

Dolomite: CaMg(CO3)2

Mineral Properties

• Crystal Form• Cleavage/

Fracture• Color• Streak• Luster

• Crystal Form• Cleavage/

Fracture• Color• Streak• Luster

• Hardness• Tenacity• Specific Gravity• Acid Test

Magnetism

• Hardness• Tenacity• Specific Gravity• Acid Test

Magnetism

Some minerals strongly attract magnets. Characteristic of magnetite and some other iron minerals

Mineral Properties

• Crystal Form

Cleavage/Fracture

• Color• Streak Color• Luster

• Crystal Form

Cleavage/Fracture

• Color• Streak Color• Luster

• Hardness• Tenacity• Specific Gravity• Acid Test• Magnetism

• Hardness• Tenacity• Specific Gravity• Acid Test• Magnetism

Fracture - any breakage that is not cleavage

Cleavage: Breaks along planes of weakness

See the way light reflects back at you (I cannot see this for you). Rotate the mineral to “find” reflective surfaces.

When you find a cleavage plane, rotate

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conchoidalfracture

Characteristic of quartz, chert and flint

Fig. 02.23

conchoidal fracture

Mineral Properties

• Crystal Form

Cleavage/Fracture

• Color• Streak Color• Luster

• Crystal Form

Cleavage/Fracture

• Color• Streak Color• Luster

• Hardness• Tenacity• Specific Gravity• Acid Test• Magnetism

• Hardness• Tenacity• Specific Gravity• Acid Test• Magnetism

Cleavage - tendency to split along planes of weakness corresponding to weaker chemical links in internal structure of crystal

One Direction of Cleavage

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AlphabeticalPage 90