Minerals
A mineral is a naturally occurring, inorganic solid with a specific chemical composition and a definite crystalline structure.
Naturally occurring means formed by natural processes, so that DOES NOT include synthetically created diamonds and other gems.
Inorganic means that they aren’t alive, and never were. Therefore coal and sugar would NOT be minerals.
Solids with a specific composition mean that they are solids, not liquids or gases. It also means that they are made up of specific elements or compounds. Quartz is made up of silicon and oxygen. Other minerals may also be made up of silicon and oxygen, but quartz has a specific arrangement and proportion of these elements that is unique to quartz.
A crystal is a solid in which the atoms are arranged in repeating patterns.
Minerals from Magma-the type and amount of elements in magma help determine which minerals will form. If the magma cools slowly, beneath the earth’s surface, the large crystals will grow. If the magma reaches the surface and therefore cools quickly, the minerals sizes will be small. One example of a rock that forms from magma is granite.
Minerals from Solution-when crystals precipitate (sink) out of a solution, or when the liquid evaporates, leaving the crystals behind. One example is gypsum.
Mineral groups-there are 3000 minerals found in the Earth’s crust, but only about 30 of these are common.
Identifying minerals-
Color-sometimes caused by the presence of trace elements or compounds in a mineral.
Luster-the way that a mineral reflects light (metallic or nonmetallic)
Texture-how it feels to the touch, such as smooth, rough, ragged, greasy, soapy or glassy.
Streak-the color of a mineral when it is broken up and powdered. Usually we drag the rock across a porcelain plate to see its streak color.
Hardness-how easily a mineral can be scratched. Moh’s Hardness Scale is a scale in which an unknown mineral’s hardness is compared to the known hardness or ten minerals.
Cleavage and fracture-how a mineral breaks. If it breaks cleanly, along certain planes, then it is said to have cleavage. If it breaks jaggedly, then it is said to have fracture.
Density- is mass divided by volume.
Mineral Uses-
Ores-a mineral that contains a useful substance that can be mined for a profit, such as iron.
Gems-valuable minerals prized for their beauty and rarity. Examples-diamond, ruby, sapphire, etc.