Chapter 3: section 1

A mineral is a naturally occurring, inorganic solid with a definite chemical composition and an orderly arrangement of atoms. ***All minerals share these four characteristics.***

Naturally occurring Meaning made by natural process NO HUMAN INPUT Inorganic solid Meaning they are not made by life processes with a definite chemical composition. Example: Halite’s (salt) is NaCl *If it is formed by the natural evaporation of sea water in laboratories, it is NOT a mineral. and an orderly arrangement of atoms Minerals are crystalline solids and all solids have a definite volume and shape. This excludes gases and liquids. Only a solid can be a mineral, but not all solids are minerals. Ex. Your desk is not a mineral.

Crystalline means that atoms are arranged in a pattern that is repeated over and over again. You can see evidence of the orderly and

Crystals form two ways: 1) Crystals form from magma 2) Crystals form from solutions of salts

1) Hot melted rock called magma cools when it reaches the Earth’s surface. 2) As magma cools, its atoms lose heat energy, move closer together, and begin to combine compounds. 3) During this process, atoms will arrange themselves in organized, repeating patterns. 4) The type and amount of elements present in a magma determine which minerals will form. 5) The size of the crystals forming depends on how quickly the magma cools.

When magma cools slowly, the crystals are usually large enough to see. When magma cools rapidly, the crystals formed will be small and difficult to see.

Crystals can form from minerals dissolved in water. When water evaporates, ions that are left behind can come together to form crystals like halite (salt).

Only 8 elements form approximately 98% of the Earth’s crust. The most common rock-forming minerals belong to a group called silicates. Silicates are minerals that contain (Si) and oxygen (O) and usually one or more other elements. Silicon and oxygen are the two most abundant elements in the Earth’s crust.