Earth’s Materials Minerals – The building blocks of the Earth

Minerals Minerals are substances which are Naturally occurring Solid Inorganic Definite composition Definite atomic arrangement

Minerals There are approximately 4000 known minerals (some common, some rare) All are compounds of elements. Most minerals are composed of 8 elements

Common Elements of Earth’s Crust NameElement Symbol Percent by mass (crust) OxygenO46.6% SiliconSi27.7% AluminumAl8.1% IronFe5.0% CalciumCa3.6% SodiumNa2.8% PotassiumK2.6% MagnesiumMg2.1% Other1.5%

Mineral Properties and Identification – (Reference Tables) 1. Luster – Metallic or non-metallic The way light shines off a fresh surface of the mineral Most minerals are non-metallic

Mineral Properties/ID 2. Hardness The resistance a mineral has to being scratched

Moh’s Hardness Scale

Mineral Properties/ID 3. Cleavage/Fracture Cleavage is the tendency of a mineral to break along zones of weakness and form smooth, parallel sides. Fracture is the tendency of a mineral to break in random directions

Mineral Properties/ID Color and Streak The color of a mineral can be useful, HOWEVER, it can vary due to slight chemical differences The streak is the color of freshly crushed mineral powder and is usually constant.

Mineral Properties/ID Using the Reference Tables

Mineral Formation 1 From Magma (molten rock) – Magma (very hot) begins to cool – As the magma cools, atoms and molecules begin for form compounds – Compounds merge together to form mineral grains – Many different minerals can form out of one ‘batch’ of magma

Mineral Formation 2 Recrystalization – A rock is subjected to high temperature and pressure – Some minerals begin to chemically change without melting – Atoms and molecules recombine in a new way and minerals begin to grow