Minerals What is a Mineral Naturally occurring Inorganic

Minerals

What is a Mineral? �Naturally occurring �Inorganic �Solid �Crystal structure �Definite chemical composition

How do we ID Minerals? � Color � streak � Luster � Density � Hardness � Crystal forms � Cleavage � Special and fracture properties (not all minerals have these)

Color

Luster

Streak

Density

Hardness

Crystal Form

Cleavage and Fracture

Special Properties Smell Taste Fluorescents

How minerals form �From magma and lava �From solution �Evaporation �Hot water solution

How Minerals Form In general, minerals form in two ways: • By crystallization of magma & lava • By crystallization of materials dissolved in water.

Minerals From Magma & Lava Minerals form as hot magma cools inside the crust or when lava hardens on the surface.

Crystallization is the process by which atoms are arranged to form a material with a crystal structure.

A geode is a rounded hollow rock that is often lined with mineral crystals.

The size of the crystal depends upon several factors: • The rate (speed) at which the molten material cools. • The amount of gas in the molten material. • The chemical composition of the molten material (or what elements/chemicals make up the molten rock.

Magma deep inside the earth takes thousands of years to cool. Slow cooling results in large crystals.

Magma close to the earth’s surface or lava that cools on the surface will cool more quickly.

Rapid cooling results in small crystals…. sometimes microscopic.

Minerals From Solutions Elements/Compounds that form minerals may sometimes be dissolved in water to form a solution.

When elements/compounds that are dissolved in water leave a solution, crystallization can occur.

Minerals Formed by Evaporation Some minerals form when solutions evaporate. Large deposits of halite in the USA formed this way.

Minerals From Hot Water Solutions Underground, magma can heat water to high temperatures. Elements/Compounds may become dissolved in this hot solution.

When the water solution cools the elements and compounds crystallize as minerals.

Pure metals that crystallize from hot water solutions underground often form veins.

A vein is a narrow channel or slab of a mineral that is different from the surrounding rock.

Uses of minerals � Gemstones � Metals � Food � Medicines � Fertilizers � Building materials

How do we get minerals so we can use them? � First we have to prospect for them � Next we have to mine them � 3 types of mines �Strip �Open pit �Shaft � Next comes processing � Smelting- separates useful metal from other elements � Further processing to remove impurities