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

1. Quartz (milky)

2. Quartz (rose)

3. Quartz (smokey)

4. Quartz, agate

5. Quartz, amethyst

6. Quartz, jasper

Types of Quartz (not the complete list)

Classes of Nonsilicates

1. Iron ores

• Contain iron (Fe)

• Example: magnetite (Fe3O4)

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)

Classes of Nonsilicates…

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