minerals. a mineral is… naturally occurring – made by nature – not by man
Post on 16-Dec-2015
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Basics of Crystals
• Crystals are defined by the number of sides (faces) and the angles of these sides (geometry)
2. Tetragonal
• tetragonal – 4 rectangles, 2 squares
3. Orthorhombic
• orthorhombic – all rectangles, 3 different sized rectangles
6. Hexagonal
• hexagonal - six-sided prisms. When you look at the crystal on-end, the cross section is a hexagon
Mineral Groups
• Minerals are often grouped together by their composition (what they are made of)
• There are over 4,000 known minerals and only 7 groups
4. Sulfides and 5. Sulfates
• Sulfides (contain Sulfur), Sulfates contain SO4
• Ex. Gypsum, Galena, Pyrite
6. Halides
• Contain halogens (Fluorine, Chlorine, etc.)• Ex. Halite, Fluorite
How do Minerals form?
• 1. Cooling magma or lava• 2. Hydrothermal• 3. Evaporation of liquid solutions• 4. Precipitate out of solution
5 Characteristics Used to Identify Minerals
• 1) Hardness• 2) Break Tendency• 3) Luster (metallic/non-metallic)• 4) Streak• 5) Color
2) Break Tendency• Fracture - breaks
along rough, jagged edges
• Cleavage – breaks along smooth, flat surfaces
Conchoidal fracture – curved breakage
Other ways to identify minerals
• Reactivity with acids• Density/specific gravity• Magnetism• More special properties to come
Other Properties of Minerals
• Reactivity with Acid• Magnetic• Fluorescence• Phosphouresence• Density• Crystal Shape• Triboluminesence
Reactivity with acid
• Carbonate minerals fizz when acid is applied
Magnetic• Some iron rich
minerals are magnetic
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