Minerals

Minerals

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  Minerals
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  What is amineral? Inorganic – not alive Solid – not liquid, or gas Naturally occurring not formed by man, but nature Definite chemical composition Elements always the same, with known arrangement Definite crystal shape Repeating pattern of atoms in 3D
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  Formation of MineralsMagma cooling Slow cooling – large crystals Fast cooling – small crystals Very fast cooling - no crystals Solution evaporation Salts and geodes Common elements Si, Al,Ca, K, O 2 , Fe, Na, Mg
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  Minerals Everyday Mineralogists – study minerals Rocks are combinations of minerals Ores - rocks from which valuable minerals are removed (usually metals) Gems – rare, “pretty,” not soft Diamonds, rubies, emeralds
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  Luster Way thesurface reflects light General: Metallic and Non-metallic More specific: Vitreous (glassy) -- example: quartz, tourmaline Adamantine (brilliant) -- example: diamond Resinous (like resin or sap from a tree) -- example: sphalerite Greasy or waxy -- example: turquoise Pearly -- example: talc Silky -- example: asbestos Dull or earthy -- example: bauxite
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  Crystal Shape Arrangementof atoms form crystal structure Types- Cubic Orthorhombic Tetragonal Hexagonal Triclinic Monoclinic
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  Color Easily identifiabletrait – but,not reliable Color can change Impurties - Yellow diamonds Oxidation – rusting, tarnish Weathering
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  Streak mineral isrubbed firmly across a white tile it leaves a line of powder. color of the streak is always the same Example: quartz leaves a white streak, whether it's violet (amethyst), pink (rose quartz), or brown (smoky quartz).
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  Transparency how welllight passes through a mineral Three degrees of transparency: Transparent – you can see through Translucent – see light , but not objects Opaque - can't see anything
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  Hardness Mohs HardnessScale - 1812 Scale used to tell how hard (10) or soft (1) a mineral is Commonly used substitutes: Fingernail – 2.5 Penny – 3.5 Glass – 5.5
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  Diamond (C) 10Corundum (Al 2 O 3 ) 9 Topaz (Al 2 SiO 4 (OH-,F-) 2 ) 8 Quartz (SiO 2 ) 7 Orthoclase Feldspar (KAlSi 3 O 8 ) 6 Apatite (Ca 5 (PO 4 ) 3 (OH-,Cl-,F-)) 5 Fluorite (CaF 2 ) 4 Calcite (CaCO 3 ) 3 Gypsum (CaSO 4 ·2H 2 O) 2 Talc (Mg 3 Si 4 O 10 (OH) 2 ) 1 Mineral Hardness
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  Used in jewelryand cutting tools. Four times as hard as corundum. Diamond 10 Sapphire and ruby are varieties of corundum. Twice as hard as topaz. Corundum 9 The November birthstone. Emerald and aquamarine are varieties of beryl with a hardness of 8. Topaz 8   Quartz 7 Orthoclase is a feldspar, and in German, "feld" means "field". Orthoclase 6 When you are hungry you have a big "appetite". Apatite 5 Fluorine in fluorite prevents tooth decay. Fluorite 4 Limestone and most shells contain calcite. Calcite 3 Plaster of paris. Gypsum is formed when seawater evaporates from the Earth’s surface. Gypsum 2 Talcum powder. Talc 1 Associations and Uses Mineral Hardness
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  Hardness of someother items: Hardened steel file 7+ Iron pyrite 6.5 Glass 6-7 Knife blade 5.5 Iron 4-5 Platinum 4-4.5 Copper penny 3 Gold, Silver 2.5–3 Fingernail 2.5
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  Cleavage When brokenminerals break along planes of weakness Related to crystalline structure Some break along 1 plane, others 2 planes
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  Fracture The waya mineral without cleavage breaks Not all minerals cleave easily Some fracture can be smoothly curved, irregular, jagged or splintery.
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  Specific Gravity isthe ratio of the density of a material compared to the density of water 1g/ml. Materials greater than 1 will sink. Materials less will float. Density of the mineral 4-6 Heavy Cordrundum, most metals 19 Heaviest Gold, platinum 3-4 Medium Heavy Fluorite, beryl 2-3 Medium Quartz 1-2 Light Graphite Specific Gravity Density Mineral
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  Special Properties toID minerals Taste – salt, NaCl Smell – sulfur, S Magnetic – magnetite Fluorescent – glow in the dark (UV) Optical double vision - calcite