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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