Category: Notes
What is a mineral?
-A mineral is a compound made up of one or more elements.
-A mineral forms naturally (it is not man-made).
-A mineral is made of materials that were never alive.
-Minerals have the same chemical makeup (they are made of the same compounds) no matter where they are found.
-Minerals have atoms arranged in regular patterns and form solid units called crystals.
-There are about 2,000 different known minerals.
-Examples of minerals:
Gold (Au)
Sulphur (S)
Aluminum (Fe)
Copper (Cu)
Iron (Fe)
Halite (NaCl)
Graphite (C)
Galena
Azurite
Malachite
Mica
Quartz
What is NOT a mineral?
-Anything that contains material from a once-living organism. This includes fossil fuels like coal and petroleum, and coral or pearls.
-Anything that contains more than one mineral is called a rock.
Minerals are recognized by their common characteristics:
Color – Some minerals can be many different colors, but others are always the same color. For example, sulfur is yellow.
Luster – The amount of light reflected from the surface of a mineral. Can be glassy, metallic, shiny, dull, waxy, satiny, or greasy.
Streak – Some minerals leave a colored streak when you “write” with them on an unglazed white tile. This may not be the same as the mineral’s color. Hematite is usually gray, but its streak is always reddish.
Texture – The feel of the mineral when it is rubbed. can be rough, smooth, bumpy, or soapy.
Hardness – Some minerals can be scratched more easily than others. We use the Mohs’ Hardness Scale of 1-10 to determine what material will or will not scratch the surface of a mineral.
Cleavage – This is the angle at which a mineral breaks. Some minerals have no cleavage, and just break into rough pieces. This is called fracture. Others break into specific shapes, like flat sheets or cubes.
Other properties – Some minerals may be magnetic, which can be tested by trying to stick a small magnet to the sample. Other minerals may bubble when exposed to hydrochloric acid (HC
