Notes on Minerals

Minerals

• Naturally occurring substances that are inorganic
• Some minerals are comprised of just one element
• Such minerals are Sulfur, graphite and diamond.
• Some minerals are made of one compound

Minerals are the substances that rocks are made of.

The earths crust is made of about 20 minerals.

Properties

• Color
• Luster
• Streak
• Crystal Structure
• Fracture/Cleavage
• Hardness
• Density
• Other

Mineral Identification Tests

Luster:  The quantity and quality of light reflected from the surface

Metallic:  looks like a metal

Non-metallic:  Does not look like a metal

Color:  Obvious, but not always definitive.

Streak:  The color of the mineral as it is powdered.

Hardness:  the resistance of the mineral to scratching.

            Mohs Hardness Scale

                                    Hardness    Index Mineral

1.      Talc

2.      Gypsum

3.      Calcite

4.      Fluorite

5.      Apatite

6.      Orthoclase

7.      Quartz

8.      Topaz

9.      Corundum

10.  Diamond

Fracture:  Rough edges and just breaks

Cleavage:  The mineral splits along closely spaced parallel lines

Minerals can be used as Gems or Ores.

Amethyst is a variety of quartz that contains impurities that color it.  Pure quartz is colorless.

Titanium is lightweight and durable.  Ilmenite and rutile are both ores of Titanium