What are they? Why are they important? How are they
identified?
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What are minerals? A naturally forming inorganic (non-living)
solid Crystal structure due to internal arrangement of atoms.
Specific chemical composition
Slide 3
Minerals are inorganic Never been alive Example: copper,
quartz, calcite. Fossils are NOT minerals- they were once living
Natural gas and oil are NOT minerals- they came from once- living
organisms
Slide 4
Why are minerals important? Essential natural resources If it
cant be grown it must be mined Mining is taking valuable minerals
out of the Earth.
Slide 5
What do we mine for? Metals- buildings, homes, plumbing,
electrical, manufacturing, transportation Rocks- buildings, roads,
manufacturing Jewelry, currency, art Health, medicine
Slide 6
Slide 7
Mineral Identification Properties 1. Hardness 2. Luster 3.
Streak 4. Color 5. Cleavage 6. Fracture
Slide 8
Mohs Hardness Scale Hardness is the ability to scratch another
mineral Mohs uses 10 relatively common minerals to compare their
relative hardness Uses common items of known hardness to compare
with ten minerals (fingernail, steel nail, glass plate, copper
penny) Very important in mineral identification
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Mohs Hardness Scale 1. Talc Softest mineral 2. Gypsum Gypsum
can scratch talc.
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Mohs Hardness test A fingernail can scratch both talc(1) and
gypsum(2) A fingernail is assigned the hardness number of 2.5
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3. Calcite Calcite can scratch gypsum 4. Fluorite fluorite can
scratch calcite and softer minerals
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Mohs Hardness Test A copper penny has a hardness of 3 A copper
penny can scratch minerals softer than a 3
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5. Apatite Can scratch Fluorite 6. Potassium Feldspar K-spar K
spar can scratch all softer minerals. None of the softer minerals
can scratch it.
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7. Quartz so hard it can scratch glass 8. Topaz Topaz is harder
than quartz
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9. Corundum Can scratch Topaz 10. Diamond is the hardest
natural substance known It is harder than all other minerals
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Luster Quality and intensity of light reflecting off the faces
of the crystal Non-metallic Metallic
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Non-metallic luster Shiny like a metal Metallic luster Dull/
Earthy Waxy, greasy or soapy Glassy Pearly Silky
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Vitreous luster Glasslike Most common Ex. Quartz
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Waxy Luster Has the look of wax Examples: chert,
smithsonite
Silky Luster Looks like silk Used to describe fibrous minerals,
such as asbestos
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Metallic Luster Looks like shiny metal Copper, silver, gold,
platinum,
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Mineral Streak The color of the powder left when a mineral is
rubbed on a streak plate The ability/inability of a mineral to
create a streak helps ID it
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Mineral Streak When rubbed on a ceramic tile, some minerals
leave certain color streaks. (EX) Grey hematite leaves a red
streak
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Color Color is based on what wavelength of light is absorbed
and reflected. Color is the LEAST reliable mineral ID test Many
different minerals have the same color. The same mineral can often
have different colors
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ID by color Sulfur copper
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Same mineral- Different colors quartz
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Same Color- Different Minerals Gypsum Calcite Albite
Halite
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Cleavage How a mineral breaks or splits along planes of their
crystal structure Cleaves along the same parallel plane over and
over again Occurs in minerals with specific planes of weakness
Several different types of cleaving
Fracture Mineral breaks along uneven lines and results in rough
and curved surfaces. Conchoidal Fracture- looks like a clam shell.
Due to atomic configuration.
Slide 35
Other Properties used to ID minerals Magnetism Acid test
calcium bubbles when touched with an acid: calcite Fluorescence
glow under UV light Salty- contain naturally occurring salt:
(halite)