What is a mineral? 5 Characteristics of a mineral • Naturally Occurring • Inorganic (Not Living) • Always a solid • Has a definite chemical composition • Atoms are arranged in a repeating pattern (creates crystals)
Mineral Identification • Scientists identify mineral based on their properties. • Color and appearance are 2 clues that we use to identify minerals. • Are color and appearance enough? • No WAY!
Hardness • The measure of how easily a mineral can be scratched by other minerals. • To compare hardness a list of common minerals and their hardness was developed by Friedrich Mohs. • We call is the Mohs scale. 1 = Softest, 10 = Hardest.
Luster • Luster describes how light is reflected from a minerals surface. • Luster is either metallic (shiny and metal – like) or non-metallic (not shiny)
Color • The color of a mineral can serve as a clue to it’s identity. • However, color is NOT enough to determine the identity of a mineral. • Ex: Quartz
Streak • Streak is the color of a mineral when it is broken down into a powdered form. • When a mineral is rubbed across a Streak Plate, the mineral that is left behind is powdered. • The streak test will only work for minerals that are softer than the streak plate. • Why?
Cleavage and Fracture • Cleavage is a property that minerals have when they break along smooth, flat surfaces. • Fracture is a property that minerals have when they break along rough, jagged surfaces.
Other Properties • Some minerals are magnetic (Ex: Magnetite) • Some minerals fizz when they come in contact with an acid. (Ex: Calcite)
Video Clip Questions • How many minerals found in nature? • About how many are important in developing rocks? • How many properties tests are used to identify minerals? • Which is more dense? Nonmetal base or metal base?