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Chapter 2 MineralsChapter 2 MineralsRemember >>>> The Earth is made Remember >>>> The Earth is made
of of mattermatter
Matter- anything that has mass & anything that has mass & takes up spacetakes up space
Most Most solidsolid matter on Earth is either: matter on Earth is either:
• a a mineralmineral
• a a rock rock (but a rock is just a (but a rock is just a mixturemixture of minerals)of minerals)
What is a Mineral ?What is a Mineral ?
- Natural (not man-made)- Natural (not man-made)- - InorganicInorganic (never living) (never living)
- - SolidSolid
- Has an orderly structure of - Has an orderly structure of atomsatoms
- Has a definite - Has a definite chemical compositionchemical composition
Minerals:Minerals:
Locating and Mining Minerals
• Minerals can be found in:• Rocks
• Sand
• Soil
• Seashells
• Below Earth’s surface
• Minerals are dug or mined out of the earth
• People mine for minerals on every continent except for Antarctica
• Minerals can be strip-mined or dug far below the earth’s surface
• Often minerals need to be separated from rock.
• Geologists can melt the minerals or use chemicals to break apart the rock
So how do we identify minerals?
How do I identify different How do I identify different minerals ?minerals ?
• COLOR• Color is not always good to use• All of these are quartz
Use 7 other properties to Use 7 other properties to identify minerals:identify minerals:
1.1. StreakStreak = color of mineral in = color of mineral in powderedpowdered form form
- rub - rub mineralmineral across a across a streak streak plateplate to see the to see the color color
7 Mineral Properties Cont…2. 2. LusterLuster = how = how lightlight reflects off reflects off surface surface
of mineralof mineral
A. A. MetallicMetallic = looks like shiny = looks like shiny metalmetal
B. Vitreous (B. Vitreous (glassyglassy) = shines like ) = shines like glassglass
C. Dull C. Dull
D. D. WaxyWaxy
7 Mineral Properties Cont…7 Mineral Properties Cont…
3. 3. Crystal FormCrystal Form = outward = outward shapeshape of mineralof mineral
- as mineral - as mineral growsgrows in size it will in size it will alwaysalways keep the same keep the same crystal crystal formform
A. A. CubicCubicB. Sheet-LikeB. Sheet-LikeC. Rhombohedral C. Rhombohedral D. D. MassiveMassive = no crystal form = no crystal form
7 Mineral Properties Cont…
4. 4. HardnessHardness = resistance of mineral to being = resistance of mineral to being scratchedscratched- rub 2 minerals together, the harder mineral will scratch - rub 2 minerals together, the harder mineral will scratch the softer mineralthe softer mineral- use the - use the Moh’s Hardness ScaleMoh’s Hardness Scale to find hardness range to find hardness range for minerals:for minerals:
1 - Talc1 - TalcSOFTESTSOFTEST
fingernail 2.5fingernail 2.5 2 - Gypsum2 - Gypsum3 - Calcite3 - Calcite
steel nail 4.5steel nail 4.5 4 - Fluorite4 - Fluoritemanufactured glass 5.5manufactured glass 5.5 5 - Apatite5 - Apatite
6 - Orthoclase6 - Orthoclase7 - Quartz7 - Quartz8 - Topaz8 - Topaz9 - Corundum9 - Corundum10 - Diamond 10 - Diamond HARDESTHARDEST
7 Mineral Properties Cont…7 Mineral Properties Cont…
5. 5. CleavageCleavage = tendency of a mineral to break along = tendency of a mineral to break along smooth, even surfaces (always in the same smooth, even surfaces (always in the same direction/directions)direction/directions)
A. A. 1 Direction1 Direction = always breaks into sheets = always breaks into sheets EX: Muscovite & BiotiteEX: Muscovite & Biotite
B. B. 2 Directions @ 90°2 Directions @ 90° = mineral always breaks into = mineral always breaks into squaressquares
EX: GalenaEX: GalenaC. C. 3 Directions @ 90°3 Directions @ 90° = mineral always breaks into = mineral always breaks into
cubes cubes EX: HaliteEX: Halite
Some minerals do not display cleavage, this property Some minerals do not display cleavage, this property is called is called Fracture Fracture EX: QuartzEX: Quartz
7 Mineral Properties Cont…7 Mineral Properties Cont…
6. Density 6. Density ((Specific GravitySpecific Gravity) ) = how = how heavyheavy a mineral feels a mineral feels
EX: EX: GalenaGalena is very is very heavyheavy for for its its sizesize
EX: EX: TalcTalc is very is very light light for its for its sizesize
7.7. OtherOther Properties Properties
A.A. Smell Smell = some mineral have a distinct smell = some mineral have a distinct smell
EX: EX: SulfurSulfur smells like smells like rotten eggsrotten eggs
B. Feel = some minerals feel B. Feel = some minerals feel greasygreasy
EX: GraphiteEX: Graphite
C. C. MagneticMagnetic = some minerals behave as = some minerals behave as magnetsmagnets
EX: MagnetiteEX: Magnetite
D. D. TasteTaste = = salty taste salty taste of Halite of Halite
CAUTION: DO NOT TASTE ANY MINERALCAUTION: DO NOT TASTE ANY MINERAL
E. E. Reacts to AcidReacts to Acid = some minerals fix when a = some minerals fix when a weak acid (HCL) is dropped on themweak acid (HCL) is dropped on them
EX: EX: CalciteCalcite
Do I use minerals Do I use minerals ??
YESYES1.1. SaltSalt (halite) (halite)2.2. pencil lead (pencil lead (graphitegraphite))3.3. make-upmake-up (talc) (talc)4.4. window glass (window glass (quartzquartz))
How do minerals form?How do minerals form?
4 Main Ways:4 Main Ways:
1. 1. CrystalsCrystals form out of form out of magmamagma
2. Precipitate (2. Precipitate (solid formssolid forms) out of water) out of water
3. Change in 3. Change in pressurepressure and temperature and temperature
4. From 4. From hothot waterwater = (causes chemical = (causes chemical reactions to form new minerals)reactions to form new minerals)
6 Major Mineral Groups:6 Major Mineral Groups:
1. Silicates = minerals that contain elements silica, oxygen and other minor elements
EX: Quartz, Olivine, Muscovite, Biotite, Feldspar- form from cooled magma
2. Carbonates = minerals that contain oxygen, carbon, and other minor elements
EX: Calcite- form in shallow oceans
3. Oxides = minerals that contain mainly oxygen and minor elements
EX: Hematite- form in variety of environments
4. Sulfates & Sulfides = minerals that contain sulfur and other minor elements
EX: Gypsum, Galena, Pyrite- forms in hot water solutions
5. Halides = minerals that contain fluorine, chlorine, and other minor elements
EX: Halite- forms from evaporation/precipitation
6 Major Mineral 6 Major Mineral Groups:Groups:
6. Native Elements = pure single forms of minerals
EX: Gold, Silver, Copper, Sulfur, Diamond, Graphite- forms in hot water solutions
What is a gemstone?What is a gemstone?• Any mineral that can Any mineral that can
be cut, polished, and be cut, polished, and sold for a profitsold for a profit
EX: EX: - DiamondDiamond- RubyRuby (mineral (mineral
Corundum) = RedCorundum) = Red- EmeraldEmerald (mineral Beryl) (mineral Beryl)
= Green= Green- AmethystAmethyst (mineral (mineral
Quartz) = PurpleQuartz) = Purple- SapphireSapphire (mineral (mineral
corundum with corundum with impurities of titanium) = impurities of titanium) = BlueBlue