1. What is the Earth’s Crust made of?
Recall that there are 2 Types of Crust!
Oceanic Crust
Continental Crust
2 Major Differences
Thickness (Which is thinner?)
Composition (What are they made of?)
Even though they have different compositions all of the Earth’s crust is composed of …

2. sulfur
gold
Minerals
malachite
rhodochrosite

3. MINERALS
To be classified as a mineral a substance must meet all of the following characteristics:
Naturally Occurring
Generally Inorganic (not formed by life processes)
Solid Substance
Definite Chemical Formula (Composition)
Orderly crystalline structure
In summary, a mineral is a naturally occurring, inorganic solid that has a definite chemical composition and crystal structure.

4. Processes that form Minerals
Crystallization from magma
Precipitation
Pressure and temperature
Hydrothermal solutions (very hot water with dissolved substances.
Figure 12: Bornite (blue and purple) and chalcopyrite (gold) are sulfur minerals that form from thermal solutions.

5. Mineral Groups Classified based on their composition.
1. Silicates - Silicon and oxygen combine to form a structure called the silicon-oxygen tetrahedron. This silicon-oxygen tetrahedron provides the framework of every silicate mineral.
Quartz is the most common silicate mineral. A typical piece of quartz
like this contains millions of silicon-oxygen tetrahedra.
**Silicates is the most common mineral group on Earth !!!!!

6. Silicate structures Single tetrahedron = olivine
Single chains = augite
Double chains = hornblende
Sheets = mica
3D networks = quartz, feldspar

7. Mineral Groups
2. Carbonates - contain the elements carbon, oxygen, and one or more other metallic elements. Calcite (CaCO3) = limestone rock, marble
3. Oxides - contain oxygen and one or
more other elements, usually metals. Rutile (TiO2) (magma cools), corundum (Al2O3) (changes in temperature and pressure), hematite (Fe2O3) = rust (exposure to moisture in the air)
The Great Pyramid of Giza. One of the Seven Wonders of the Ancient World, the structure is made entirely from limestone.
Rusted bolt

8. halite Pyrite, fool’s gold (sulfide mineral) Gold, native element
4. Sulfates and Sulfides - contain sulfur. Anhydrite (CaSO4) (mineral rich waters evaporate), pyrite (FeS2) = Fool’s Gold hydrothermal solutions)
5. Halides - contain a halogen ion plus one or more other elements. Halite (NaCl) = table salt (salt water evaporates = precipitation)
6. Native elements - exist in relatively pure form. Gold (Au), Silver (Ag), Copper (Cu), Sulfur (S), Carbon (C) = diamond, graphite (Hydrothermal solutions)
Pyrite, fool’s gold
(sulfide mineral)
halite
Gold, native element

9. Common Uses of Minerals
copper
electrical wiring, coins
gold
computer circuitry , UV protection for astronauts
magnetite
natural magnet
halite
table salt
fluorite
toothpaste
galena
car batteries, iron extraction
molybdenite
steel and soil additive
sulfur
matches
zeolite
water softener
diamond
drills