Rocks & Mineral Identification

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Transcript Rocks & Mineral Identification

Rocks & Mineral
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
 Includes
of a known
 Other items can
be used to
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