Rocks & Mineral Identification Chapter 2

Identification Strategies  Streak –Color of a mineral in its powdered form –Rub a rock or mineral on a ceramic streak plate –Metallic minerals  Dark streak –The color of the streak may not necessarily be the color of the mineral  Color –Elements dictate the color of a mineral

Rock/Mineral ID  Luster –Used to describe how light is reflected from the rock or mineral –Metallic  looks like metal [Copper] –Glassy  Clear or shiny [Obsidian] –Silky  looks like strands of silk

Rock/Mineral ID  Hardness –Resistance to being scratched –Moh’s Hardness Scale  Includes minerals of a known hardness  Other items can be used to determine hardness

Rock/Mineral ID  Cleavage –Tendency of a mineral to cleave, or break along flat surfaces –Natural breakage of a rock or mineral –Micas have perfect cleavage = can peel off in sheets  Fracture –Uneven breakage of rock  Conchoidal – smooth, curved surfaces  Glassy – looks like glass