Minerals

A mineral: Is a naturally occurring inorganic solid Has a specific chemical makeup A mineral has a specific crystalline structure

Minerals are formed by natural processes Minerals are inorganic (not alive EVER!!!)

The atoms in a mineral are arranged in particular patterns

A crystal is a solid in that has it’s atoms in a specific repeating pattern

Remember that solids have definite shapes and volumes

They are primarily rigid They also have specific unique chemical

compositions

There are about 3000 minerals in Earth’s crust

But only about 30 are common About 8 to 10 are called rock forming

minerals because they make up most of the rocks in Earths crust

The most common elements are:◦ Oxygen 46.6%◦ Silicon 27.1%◦ Aluminum 8.1%◦ Iron 5%◦ Calcium 3.6%◦ Sulfur 2.8%◦ Potassium 2.6%◦ Magnesium 2.1%

Magma is less dense than the surrounding solid rock so it can rise upward to cool.

How it cools decides what type of rock is formed

Slowly cooled magma becomes rock with large crystals

Quickly cooled magma has small crystals

When a liquid gets full of a dissolved substance, it is supersaturated

This allows minerals to form Individual atoms bond and mineral crystals

precipitate (form into solids in the solution)

Crystal form◦ Some minerals form distinct crystal shapes that

are immediately recognized◦ Halite (table salt) forms perfect cubes◦ Quartz crystals have double pointed ends and six

sided crystals

Luster◦ Is the way a mineral reflects light◦ Two types of luster

Metallic luster and nonmetallilc luster

Hardness◦ Is a measure of how easily a mineral can be

scratched◦ Friedrich Mohs developed a scale to compare the

hardness of minerals◦ Talc is the softest and Diamonds are the hardest.

Cleavage and fracture◦ The atomic arrangement of a mineral determines

how it will break◦ They break along their weakest planes◦ A mineral that splits easily and evenly along one

or more planes is said to have cleavage

Streak◦ A mineral rubbed across an unglazed porcelain

plate can leave a colored powdered streak on the plate

◦ Streak is the color of a mineral when it is broken up and powered

◦ Non-metallic minerals usually leave just a white streak

◦ Metallic minerals leave colors although the color may not match the solid mineral color

Color◦ Is caused by the presence of trace elements or

compounds within a mineral

Learning Targets Define a mineral

Describe how minerals form

Classify minerals according to their physical and chemical properties