1. Rocks & Minerals 101

2. Minerals What is a “Mineral”? Solid, non-living substance
Crystal form (lattice structure)
Elements or Compounds
Minerals are mined from the ground
More than 2,000 kinds of minerals
20 common minerals make up 95% of Earth’s crust
All rocks contain at least one mineral

3. Minerals are a resource
Minerals include:
Metals (gold, silver)
Nonmetals (carbon, sulfur)
Fertilizers (nitrates, potash)
Ceramics (Al2O3, ZrO2)
Chemicals (salt or gypsum)
Fossil fuel minerals (oil, gas)

4. Mineral Categories Two types of Minerals: Silicate: Non-silicate:
Contain Silicon (Si) and oxygen (O)
Formed when molten rock cools (at surface or deep underground)
SiO2 (Silica) is good example
Non-silicate:
Does not have Si & O
Formed when magma cools, water evaporates
NaCl (Halite) is good example

5. Minerals are Crystals What is a “crystal”? Solid form of a substance
Atoms are arranged in a repeating pattern (lattice)—like bricks in a wall
Weathering wears down crystal surface:
Physical—gravity, running water
Chemical—dissolving or oxidation

6. Halite crystal structure

7. Crystal Structure Crystal Form Cleavage Striations
External geometric shape
Cleavage
Tendency of minerals to break along planar surfaces
Striations
Closely spaced lines on the cleavage face

8. Physical Properties of Minerals
Color
Streak
Color of a finely powdered mineral
(rub on a porcelain plate)
Luster
Appearance of a mineral surface as it reflects light
Hardness
Mohs Hardness Scale

9. Hardness of Minerals Mohs hardness scale (Frederich Mohs, 1800)
Mohs scale number (mineral example): 1 (Talc) 2 (Gypsum) 3 (Calcite) 4 (Fluorite) 5 (Apatite) 6 (Orthoclase Feldspar) 7 (Quartz) 8 (Topaz) 9 (Corundum) 10 (Diamond)

10. Mohs hardness scale (con’t)
Hardness of other common objects: Fingernail: 2.5 Copper penny: 3 Glass: 5.5

11. Rocks Rocks are made of minerals Solid materials of Earth’s crust
3 Classes of Rocks:
Igneous
Metamorphic
Sedimentary

12. Igneous Rocks Cooling & solidification of hot fluid rock:
Magma -
Lava -
Two subcategories:
Extrusive (from lava; Ex: pumice, Basalt)
Intrusive (from magma; Ex: Quartz, Granite)

13. Metamorphic Rocks Undergoing change “metamorphosis”:
Heat (200 C to > 800 C)
Pressure
Deep in Earth’s crust (5 – 65 km)
Minerals changed chemically
Examples (sedimentary  metamorphic):
Shale  Slate
Limestone  Marble
Sandstone  Quartzite

14. Sedimentary Rocks At Earth’s surface Deep burial of sediment:
Erosion of the 3 major types of rocks
Sediment collects in low spots (basins, lakes)
Deep burial of sediment:
High Pressure
High Temperature (300 C)
Squeezes soft sediment
Cementing of sediment  rock
Cement forms between grains of sediment
Takes long time! (10,000 to 100,000 years)

15. Sedimentary Rocks: 3 Types
Clastic:
From broken bits of rock
Ex: Sandstone, Shale
Chemical:
Chemical precipitation from solution
Ex: Halite (NaCl), Gypsum (CaSO4)
Organic:
From fossils (remains of ancient plants & animals)
Ex: Coal, Limestone

16. Rock Cycle How rock types are linked in time & space
Weathering, gravity break down all 3 rock types  sediment
Sediment  accumulates  cemented to Sedimentary rock OR  Squeezed, broken, melted  Igneous/Metamorphic