Minerals
4 requirements to be considered a mineral: Naturally Occurring (not manmade)
4 requirements to be considered a mineral: Inorganic – not from living things Arsenic minerals
4 requirements to be considered a mineral: Unique chemical composition (chemical formula) Calcite
4 requirements to be considered a mineral: Definite structural pattern (crystalline) Quartz
Relationship to Rocks Are minerals rocks? Yes Are all rocks minerals? Not always Why? Not all rocks fit the criteria of a mineral
Mineral Formation Precipitation: minerals settle out of solution Crystallization: structured organization of atoms Crystal size: depends on amount of time to grow
Physical Properties: Color – this is the LEAST RELIABLE One mineral can come in many colors Many minerals can be the same color Quartz
Physical Properties: Streak – the color of the mineral in powdered form May be different than its color More reliable Pyrite
Physical Properties: Luster – how it shines or reflects light Metallic (shiny) vs. nonmetallic (dull, glossy) Metallic Luster Nonmetallic Luster
Physical Properties: Hardness – resistance to being scratched Moh’s hardness scale Ranges from 1 (soft) to 10 (hard)
Hardness Each number is a different mineral Ex: 1= Talc, 10=Diamond, 7= Quartz
Hardness The hardness of tools used to identify minerals can also be on the scale Ex: Fingernail = 2.5 Penny = 3.5 Glass = 5.5 Steel nail = 6.5
Physical Properties: Cleavage – tendency of a mineral to split along planes of weakness Up to 3 planes
Physical Properties: Fracture – uneven breaks (no cleavage)
Other Possibly Useful Properties: Magnetic
Other Possibly Useful Properties: Taste (not recommended) Ex: Halite
Other Possibly Useful Properties: Acid test – some minerals bubble in hydrochloric acid Ex: Calcite
Other Possibly Useful Properties: Double Refraction – can see two images through the mineral Ex: Calcite
Other Possibly Useful Properties: Fluorescence: glow under UV light
***IMPORTANT: The physical properties of a mineral are due to the internal arrangement of its atoms!***
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