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) 2 SiO 4 ) [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. 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

Quartz SiO 2 Hardness = 7 Rose Quartz SmokeyQuartz Quartz Citrine AmethystAmethyst Carnelian Onyx Jasper

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

Streak : Color of powdered mineral on porcelain plate Hardness ~ 6.5 Good for metallic opaque minerals, Not good for silicates, transluscent/transparent minerals, and minerals harder than the streak plate (color of streak plate) PyriteHematite

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 Specific Gravity - density of the material (g/cm 3 ) Mineral Properties

Specific Gravity the atomic weight of the contained elements Related to both the atomic weight of the contained elements, and how tightly the atoms are packed Orthorhombic Carbonates All minerals have same structure, only cation differs MineralFormulaCation g/cm3 AragoniteCaCO StrontianiteSrCO WitheriteBaCO CerrusitePbCO

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 metallic pyrite gold silver

Luster quality of light reflected from mineral surface resinous pearly vitreous (glassy) non-metallic Some 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 scratching Compare 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 Muscovite Hardness < 2 Can scratch with fingernail (H=2.5) Muscovite Hardness < 2 Can scratch with fingernail (H=2.5)

Fig c 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 a 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: CaCO 3 HCl + CaCO 3 > H 2 O + Cl - + Ca + + CO 2 Dolomite: CaMg(CO 3 ) 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 Page 82

conchoidalfracture Characteristic of quartz, chert and flint

Fig 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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