Minerals Notes
Definition:
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Minerals: a naturally occurring, inorganic solid with a definite chemical composition and a particular
crystalline structure (orderly arrangement of atoms)
Naturally occurring
 Formed in processes on or in the earth with no human input
Inorganic
 Not made by living process
 *It has never been alive!
Definite chemical composition
 All minerals are elements or compounds with definite chemical composition
Crystal Structure
 The atoms of the mineral are arranged in patterns that repeat over and over again.
 Ex. Graphite versus Diamond
Uses of Minerals
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Ores - used for metals, extracted by mining (ex. iron)
Gems – rare and beautiful, often used for jewelry
Physical properties used to identify minerals:
1) Color
 This is an easy clue, but it can be misleading.
 Many different minerals have the same color and appearance…
 ex) pyrite and gold
2) Hardness
 A measure of how easily a mineral can be scratched.
 Mohs Hardness Scale
3) Luster
 The way the mineral reflects light.
 Either metallic or non-metallic.
 Nonmetallic can be: Dull, Pearly, Silky, and Glassy
4) Streak
 The color of the mineral in the powdered form.
5) Cleavage and Fracture
 Cleavage – mineral that break along a smooth, flat surface (ex. Mica)
 Not all minerals have cleavage…
 Fracture – minerals that break with uneven, rough, or jagged surfaces (ex. Halite)
Other Properties:
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Some minerals are magnetic. (Magnetite)
Some react with HCl (Calcite)
Salty Taste (Halite) - many minerals are poisonous, so DON’T TASTE THEM!!
Sulfur has a smell like rotten eggs.
Silicates
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Minerals that contain mostly silicon and oxygen
Si and O combine to form most of the minerals in Earth mantle and crust