CHAPTER 4 SECTION 2

TYPES OF MINERALS

MINERAL GROUPS

Silicates•Minerals that contain silicon and oxygen•Make up 96% of minerals in Earth’s crust•Tetrahedron

• Building block of silicates• Geometric solid having four sides that are equilateral

triangles• Resemble a pyramid• Silica tetrahedra has one silica atom and 4 oxygen atoms• Silica tetrahedron can form in a variety of combinations• Accounts for the large diversity of silicate minerals.

SILICA TETRAHEDRON

SILICATES

• Individual tetrahedra are strongly bonded• Sheets• Chains• Complex three-dimensional structures

• Bonds determine the • fracture or cleavage properties• Weak ionic bonds break along sheets- mica

CARBONATES

• Minerals composed of one or more metallic elements and the carbonate ion CO3

2-.• Examples:• Calcite • Dolomite• Rhodochrosite

• Found mostly in rocks such as limestone and marble• Have distinctive colorations

CARBONATES

Calcite Dolomite

RHODOCHRISITE

OXIDES

• Compounds of oxygen and metals• Hematite and Magnetite common iron oxides• Uranitite- source of uranium

Hematite

Magnetite

Uranitite

OTHER GROUPS

• Sulfides• Pyrite (fool’s gold)• Sulfur and one or more elements

• Sulfates• Anhydrite• Sulfate ion and other elements

• Halides• Halite• Chloride and fluoride along with calcium

• Native elements• Silver, or copper• Made of one element only

ECONOMIC MINERALS

• Ore• A mineral is an ore if it has value.• As soon as the value is gone, it is no longer an ore

• Gems• Valuable minerals that are prized for their rarity and beauty.• Very hard and scratch resistant• Emeralds, rubies, diamonds• Polished and use for jewelry

Platinum ore