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.

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MineralMineral - A naturally occurring, inorganic, - A naturally occurring, inorganic, homogeneous solid with a definite chemical composition homogeneous solid with a definite chemical composition and an ordered atomic arrangement. 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 Crystal symmetry is controlled by the atomic structure of mineralatomic 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

QuartzQuartzSiO2

Hardness = 7

Rose QuartzRose QuartzRose QuartzRose Quartz

SmokeySmokeyQuartzQuartz

QuartzQuartzCitrineCitrine

AmethystAmethystAmethystAmethyst

CarnelianCarnelian

OnyxOnyxJasperJasper

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

hematite streak colorhematite streak color

• 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 GravitySpecific Gravity - density of the material (g/cm3)

Mineral Properties

Specific GravitySpecific Gravity

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

Orthorhombic CarbonatesOrthorhombic 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

See Page 82 in Lab Manual for Specific Gravities of some

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

Luster - quality of light reflected from mineral surface

LusterLuster - quality of light reflected from mineral surface- quality of light reflected from mineral surface

metallicmetallicpyrite

goldgold

silversilver

LusterLuster quality of light reflected from mineral surfacequality of light reflected from mineral surface

resinouspearly

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

Mohs Hardness ScaleMohs Hardness ScaleAustrian mineralogist F. Mohs, 1824

Based on relative hardness of 10 common minerals

Based on relative hardness of 10 common mineralshardhard

softsoft

10. Diamond C9. Corundum Al2O3

8. Topaz Al2SiO4(F,OH)2

7. Quartz SiO2

6. Orthoclase KAlSi3O8

5. Apatite Ca5(PO4)3(F,Cl,OH)4. Fluorite CaF2

3. Calcite CaCO3

2. Gypsum CaSO4

1. Talc Mg3Si4O10(OH)2

Higher numbered minerals scratch lower numbered minerals

fingernailcopper penny

glass plate

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 TestAcid Test• Magnetism

• Hardness• Tenacity• Specific Gravity

Acid TestAcid Test• Magnetism

Reaction to dilute acid; especially useful in identifying carbonate minerals

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

FractureFracture - any breakage that is not cleavage

conchoidalconchoidalfracturefracture

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

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

A single crystal can display several cleavage directions.

The cleavage directions are not always at right angles to each other. They The cleavage directions are not always at right angles to each other. They also are not necessarily parallel to the crystal faces of the mineral.also are not necessarily parallel to the crystal faces of the mineral.

1 direction 2 directions

Fig. 02.19a

One Direction of Cleavage

One Direction of Cleavage

Two Directions of CleavageTwo Directions of Cleavage

Cleavage DirectionCleavage Direction

Each set of parallel planes of weakness is one direction

Three Directions of Cleavage

Fig. 02.22http://www.geology.sdsu.edu/visualgeology

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Fluorite Crystals

Four Directions of Cleavage

Six directions of Cleavage: Sphalerite (ZnS)