Review: Minerals T/F Rocks are found inside minerals T/F Minerals are always solid T/F Rocks always have a crystal structure T/F There are 4 characteristics that make up minerals
5 Physical Properties of Minerals Color Streak Luster Cleavage Hardness
Color Most minerals have a limited color range Least accurate way to identify a mineral Different things cause color to vary Being at/near Earth’s surface Defects
Streak The color of the powder left behind when the mineral is scraped across a surface This method is much better than relying on color Wulfenite and Rubies are both red, but they have different hardness
Luster How it shines: Metallic Non-metallic Looks like it’s made of metal Non-metallic Does not look like a metal
Cleavage and Fracture How it breaks gives us more information than color and luster Fracture Breaks into irregular pieces Bonds are equal in all directions Cleavage Breaks along flat surfaces Weaker bonds Broken surfaces that are smooth
Hardness How resistant the mineral is to being scratched HARDNESS SCALE INDEX MINERAL COMMON OBJECTS 1 Talc 2 Gypsum Fingernail 2.5 3 Calcite 4 Fluorite Copper Penny 3 5 Apatite 6 Orthoclase Glass 5.5 Steel Knife 6.5 7 Quartz 8 Topaz 9 Corundum 10 Diamond How resistant the mineral is to being scratched We use Mohs scale that is listed to the side
More info on Hardness The Moh’s Hardness Scale ranks the order of hardness. For example, your fingernail can scratch the minerals talc and gypsum because those minerals have a hardness of 2 or lower. A copper penny can scratch calcite, gypsum, and talc. Any mineral can scratch glass as long as it has a hardness > (greater than) 6.