Ch 4. Minerals

What is a mineral? Naturally occurring Inorganic Solid Specific chemical composition Definite crystalline structure

Naturally Occurring Minerals are formed by natural processes They are NOT man made

Inorganic They are not alive Salt is a mineral Sugar is not because it was harvested from a plant.

Solid Solids have a definite shape and volume

Specific chemical composition Each mineral has a unique “recipe” Quartz = SiO2 Calcite = CaCO3 Some minerals consist of a single element Copper (Cu), Silver (Ag), Sulfur (S)

Definite Crystalline Structure Atoms are arranged in a regular geometric pattern Pattern is repeating Minerals that form in an open space may grow into a single, large, well-defined crystal This is rare Most crystals form in a restricted space so their internal structure is not as obvious

Formation of minerals From Magma Magma cools as it rises toward the surface of the Earth Compounds in the magma begin to interact chemically Magma cooling slowly results in LARGER crystal sizes Magma cooling very quickly results in SMALLER crystal sizes

Formation of Minerals From solution When a solution cannot dissolve anymore of a substance it is considered supersaturated This may cause mineral crystals to precipitate out of the solution The same can happen if the liquid evaporates

Mineral Groups Numbers Approximately 3000 known minerals About 30 are considered common 10 make up 90% of the Earth’s crust Oxygen, silicon, aluminum, iron, calcium, sodium, potassium, magnesium

Silicates Consist of 1 silicon atom, 4 oxygen atoms and usually one or more other elements Structure is called a tetrahedron. (pyramid) Oxygen atoms can bond with one another in several different ways Example – Olivine – Mg2SiO4

Carbonates Consist of one or more metallic elements and a carbonate group CO3 Example – Calcite – CaCO3 Carbonates are the primary minerals found in limestone and marble

Oxides Compounds of oxygen and a metal Examples – hematite and magnetite FeO3 Both are common and good sources of iron

Sulfides Compounds of sulfur and one other element Example – FeS2 - Pyrite

Sulfates Contains the sulfate compound SO4 Example – Anhydrite – CaSO4

Halides Made up of Chloride and Fluoride along with Calcium, Sodium, or Potassium Example – Halite – NaCl (salt)

Native elements Made up of a single element Example – Silver and Copper