1. Introduction to Minerals
Earth Science
Introduction to Minerals

2. What are minerals?
A mineral is a naturally occurring, homogeneous solid of definite chemical composition. It has a clear arrangement of its atoms and is formed by inorganic processes.
Most of these have specific atomic structures which can be discerned by studying the outward shape of the mineral (crystal structure). These reflect the arrangement of the atoms involved in forming the mineral.

3. Minerals, cont.
Minerals must occur naturally; coal, amber, obsidian are not minerals.
It has a chemical formula…this can have some variability due to impurities of other elements, which frequently impart different colors.

4. Minerals, cont.
Since each mineral has its own atomic make-up, each will also have its own collection of physical properties, unique to itself.
Properties:
Hardness (Moh’s scale, relative list)
Luster
Color
Shape
Density
Fracture or cleavage
Streak

5. Interesting Twists Polymorphs: same composition, different structures
Graphite, Diamond
Quartz, Tridymite, Cristobalite, Coesite
Calcite, Aragonite
Pyrite, Marcasite
Isomorphs: same structure, different compostion
Olivine: series of Mg-Fe silicates
Calcite and Rhodochrosite: Ca or Mn carbonate
Apatite series: hydroxyl-or fluoro-phosphate of calcium

6. Some Familiar Minerals: Quartz SiO2

7. Pyrite: FeS2

8. Calcite: CaCO3

9. Halite: NaCl

10. Gypsum: CaSO4-2(H2O)

11. Beryl: Al2Be3(Si6O18)