1. Chapter 3 Minerals and Rocks
Earth Materials

2. Minerals
A mineral is a naturally occurring, homogeneous solid of definite chemical composition and ordered atomic arrangement that is usually formed by inorganic processes.
A Natural Crystalline Phase

3. Minerals A mineral must occur naturally.
It must be chemically homogeneous down to the atomic level
It must have a chemical formula (eg SiO2, FeS2)
It must have a defined crystal structure.
It must be inorganic (not the result of biological processes alone).

4. Some Familiar Minerals
Quartz (SiO2)
Pyrite (FeS2)
Calcite (CaCO3)
Gold (Au)
Silver (Ag)
Copper (Cu)
Diamond (C)
Graphite (C)
K-feldspar (KAlSi3O8)
Na-feldspar (NaAlSi3O8)
Olivine (Mg2SiO4)
Garnet (Mg3Al2Si3O12)
Gypsum (CaSO4 2H2O)
Apatite (Ca5 (PO4)3OH)
Ice (H2O)
Halite (NaCl) (Salt)

5. Hydrothermal Gold

6. Halite NaCl (Salt) Occurrence: Evaporites, Salt Domes
Uses: Table salt, De-icing, Nuclear waste host rock?

7. Calcite CaCO3

8. Ice H2O

9. Quartz SiO2

10. Quartz SiO2

11. Mineral Properties
Hardness (Mohs Scale)
Luster
Color
Shape
Density

12. Some Non-Mineral Solids
Obsidian (Glass)
Opal (Amorphous)
Coal (Amorphous)
Wood (Organic)
Amber (Organic)

13. Polymorphs Same composition - different structure
Graphite - Diamond (C)
Quartz - Tridymite - Cristobalite - Coesite
Calcite - Aragonite (CaCO3)
Pyrite - Marcasite (FeS2)

14. Isomorphs Same Structure - Different Composition
Olivine (Mg2SiO4) (Fe2SiO4)
Calcite - Rhodochrosite (CaCO3) (MnCO3)
Apatite (Ca5(PO4)3OH) - (Ca5(PO4)3F)

15. Rocks are Composed of Minerals

16. A Rock is an Aggregate of Minerals
Igneous -
Crystallized from melts
Surface - Volcanic; Subsurface - Intrusive
Sedimentary -
Deposited from air and water on the surface
Metamorphic
Recrystallized from pre-existing igneous or sedimentary rocks.