1. Minerals
Aluminum
Silicate minerals
Calcium carbonate
Iron pyrite

2. Mineral – a natural, inorganic, solid found in Earth’s crust
What is a Mineral?
Mineral – a natural, inorganic, solid found in Earth’s crust
Characteristics of Minerals:
Naturally occurring (a diamond made in the lab is not considered a mineral!)
Solid
Inorganic – NOT made up or produced by living organisms or their remains
Definite chemical composition – Example: Halite is always NaCl
Definite crystal structure (Note: obsidian is melted basalt)
Crystal – a natural shape of
specific geometric arrangement
NaCl = Halite

3. How Minerals Form 4 Major Processes… Crystallization from magma
1st minerals to crystallize from magma;
rich in iron, calcium, and Mg
Precipitation
dissolved minerals precipitate out of solution
Changes in pressure and temperature
exposed to high pressure and extreme temperatures
Formation from hydrothermal solutions
dissolved minerals in extremely hot ( °)
limestone
mica
Bornite, sulfur

4. Mineral Groups

5. Silicate Minerals
All minerals are classified as either Silicate or Non-silicate.
Silicate minerals make up 96% of the Earth’s crust!
All silicates have both silicon (Si) and oxygen (O).
Most silicate minerals contain other types of atoms.
Feldspars are the most common silicate minerals.
The feldspar that forms depends on which metal combines with the SiO2
Quartz: SiO2
Orthoclase – K
(potassium)
Plagioclase – Na, Ca
(sodium &/or calcium)

6. Kinds of Minerals
Scientists have identified over 3000 different minerals.
The most common are called “Rock-forming” minerals
There are 20 “Rock-forming” minerals.
10 of these make up 90% of the Earth’s crust...
quartz calcite
orthoclase dolomite
plagioclase halite
muscovite gypsum
biotite ferromagnesian minerals

7. Feldspar and Quartz alone make up >50% of the Earth’s crust.
Ferromagnesian minerals are rich in Fe and Mg...
Including:
hornblende muscovite
olivine biotite

8. Crystalline Structure
Crystal – A natural solid with a definite shape
Silicates form in chains,
sheets, and networks
Silicon-oxygen tetrahedron

9. Nonsilicate Minerals 4% of the Earth’s crust
6 major groups, based on chemical composition (page )
Carbonates
CO3
Halides
Na, K, or Ca
with Cl or F
Native elements
Oxides
O (w/o Si)
Sulfates
SO4
Sulfides
Element combined w/S

10. Video on Minerals (~10 min)

11. 9.2 Identifying Minerals Characteristics of Minerals
Mineralogists conduct tests to identify minerals.

12. Color Some minerals have a distinct color,
Sulfur
Azurite
Cinnabar
Serpentine
...but generally, color is unreliable in identification.
All corundum

13. Luster - Light reflected from the surface of a mineral
Metallic luster – reflect light
Nonmetallic luster – glassy, waxy, pearly, brilliant
Earthy - dull

14. Streak – color of mineral in powdered form
Rub mineral against an unglazed tile

15. Cleavage and Fracture Cleavage – tendency to split along a plane
Fracture – does not break along cleavage planes

16. Moh’s Scale of Hardness
Measure of the ability of a mineral to resist scratching
Scratch Test:
Fingernail, Copper, Steel, Glass, Quartz
See scale on p. 165

17. Crystal Shape There are 6 basic crystal systems:
Isometric or Cubic pyrite
Triclinic
turquoise
Orthorhombic
topaz
Hexagonal , quartz
Monoclinic, mica
Tetragonal, zircon

18. Density – ratio of the mass to volume
Find mass: use an electronic scale
Unit – g
Find volume: measure with a ruler, or by
Unit – cm3
Density Unit is g/cm3

19. Special Properties Magnetism Double refraction Fluorescence
loadstone
Fluorescence
Phosphorescence
Radioactivity
Glows under UV
Absorb UV then reemits