MineralsChapter 3 Section 1

A mineral is◦Naturally occurring◦Inorganic- it has no carbon in its chemical formula

◦Has a definite chemical composition◦Has an orderly arrangement of atoms

◦4000 different minerals

Mineral

Crystalline- means that the atoms are arranged in a pattern that keeps repeating over and over

Atom patterns

Solid in which the atoms are arranged in orderly, repeating patterns.

Six major shapes to crystals◦Cubic◦Hexagonal◦Tetragonal◦Orthorhombic◦Monoclinic◦Triclinic

Crystals

6 major shapes of minerals

1. From Magma2. From Solution

Crystals form in 2 ways

After magma is released from below Earth’s surface it begins to cool

As it cools, atoms lose heat and move together forming compounds.

These compounds arrange themselves in regular repeating patterns or crystals

If magma cools quickly, the crystals are large

If magma cools slowly, the crystals are small

Crystals from magma

Crystals also form from minerals dissolved in water

Water can evaporate leaving crystals behind like halite or salt crystals

If too much substance is dissolved in a water then it can precipitate out forming a crystal

Crystals from solution

Most of Earth’s surface is made up of 8 minerals Oxygen- 46.6% Silicon-27.7% Aluminum- 8.1 % Iron- 5.0 % Calcium-3.6% Sodium- 2.8 % Potassium- 2.6% Magnesium 2.1% Other 1.5%

Mineral Composition

Most of the common rock forming minerals contain silicon and oxygen

They are called the silicates They contain silicon, oxygen, and 1 or 2

more elements

Mineral composition cont.