Minerals Review
Every mineral…
1. Inorganic
2. Naturally occurring
3. Crystal structure
4. Consistent chemical composition
2 Kinds of Minerals
1. Silicates: contain silicon (Si) and oxygen (O)
2. Nonsilicates: do not contain Si and O together
Silicates
• Examples:
Quartz (SiO2)
Serpentine (Mg3Si2O5(OH)4)
Muscovite (KAl2(AlSi3O10)(F,OH)2)
• Make up over 90% of Earth’s crust
• Arranged as silicon-oxygen tetrahedron
Types of Quartz (not the
complete list)
1. Quartz (milky)
2. Quartz (rose)
3. Quartz (smokey)
4. Quartz, agate
5. Quartz, amethyst
6. Quartz, jasper
Classes of Nonsilicates
1. Iron ores
•
Contain iron (Fe)
•
Example: magnetite (Fe3O4)
Classes of Nonsilicates…
2. Oxides
•
Contain oxygen (O)
•
Example: corundum (Al2O3)
Classes of Nonsilicates…
3. Sulfides
•
Contain sulfur (S)
•
Example: Pyrite (FeS2)
Classes of Nonsilicates…
4. Carbonates
•
Contain carbonate (CO3)
•
Example: Calcite (CaCO3)
Classes of Nonsilicates…
5. Micas
•
“sheet silicates” that exhibit basal cleavage
•
Examples: Muscovite and Biotite
Classes of Nonsilicates…
6. Mafic/Ultramafic
•
Minerals or rocks containing a large amount of iron
(Fe) and/or magnesium (Mg)
•
Examples:
Olivine ((Mg, Fe)2SiO4)
Serpentine (Mg3Si2O5(OH)4)
Classes of Nonsilicates…
7. Phosphates
•
Contain phosphate (PO4)
•
Example: apatite (Ca5(PO4)3(F,Cl,OH))
Classes of Nonsilicates…
8. Sulfates
•
Contain sulfate (SO4)
•
Example: Gypsum (CaSO4·2H2O)
Classes of Nonsilicates…
9. Native elements
•
Minerals that are a single element
•
Examples:
Sulfur (S)
Graphite and diamond (C)
Gold (Au)
Classes of Nonsilicates…
10. Halides
•
Contain one or more halogens, such as fluorine (F),
chlorine (Cl), and bromine (Br)
•
Examples:
Halite (NaCl)
Fluorite (CaF2)
Mineral Properties
1. Color
2. Streak
3. Fracture
4. Cleavage
5. Hardness
6. Luster
Color
• Not a good identifier
• One exception is sulfur
Streak
• Powdered form of the mineral
• Can be used to distinguish gold and pyrite
Fracture
• When the mineral breaks unevenly
• Quartz has fracture
Cleavage
• When the mineral breaks into smooth, flat planes
• Types:
Hardness
• Scratch test
Luster
• The way a mineral reflects light
• Types:
Specific Gravity
Specific Gravity…
• The higher the specific gravity, the higher the density
of the mineral
Fluorite
• Fluorescence – glows under a UV light
Quartz
• Hardness of 7
• Used to make glass
• Many varieties
Amethyst
Rose Quartz
Muscovite
• Basal cleavage
• Used to make computer chips
Biotite
• Basal cleavage
• Used in tiles
• Found in granite
Olivine
• Also called peridot, August’s birthstone
• A mafic mineral (melts at very high temperatures)
Serpentine
• A mafic mineral
• Releases water under high heat and pressure
• Can cause rock to melt at lower temperatures in
subduction zones
Pyrite
• “fool’s gold”
• Used for explosives and fertilizer
Corundum
• Hardness of 9
Magnetite
• Naturally magnetic
• An iron ore
Sulfur
• Characteristic bright yellow color
• Rotten egg or match smell
Halite
• Salt rock
Gypsum
• Used for drywall
Galena
• High density
• Metallic luster
Graphite
• Used in pencils
• Greasy feel
• Elemental carbon (C)
Hematite
• An iron ore
• Red streak
Chalcopyrite
• Softer and darker in color than pyrite
• Dark green streak
Talc
• Hardness of 1
• Used in make-up
Calcite
• Main mineral in limestone
• Effervescent – bubbles in acid
• Caves form in calcite
Malachite
• Found in association with calcite
• A carbonate
• Green color
Dolomite
• Found in association with calcite
• A carbonate
• Less effervescent than calcite