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Minerals
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What is a mineral? A mineral is a naturally occurring, inorganic solid with a definite chemical composition a crystal structure About 4,000 minerals exist Only about 100 are common Ceramic, metallic and some paper products include minerals
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Characteristics All minerals form by natural processes
No input from humans Minerals are inorganic Not made from anything that was once living Every mineral is an solid element or compound with a definite volume and shape Minerals are crystalline solids – they have definite volume and shape
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Element v/s Compound Elements are single substances composed of a single type of atom Ex: Sodium, Na and Gold, Au Compounds are two or more elements combined so that the elements no longer have distinct properties Ex: Sodium Chloride, NaCl (salt)
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Crystal Solid in which the atoms are arranged in orderly repeating patterns Can be made from magma Can be made from solution Crystals are left behind when liquid with minerals dissolved in it evaporates
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Physical Properties Hardness Luster
Color : unreliable - smoky, milky, purple, red, clear Cleavage and Fracture Specific Gravity Special properties: Feel Taste : halite Smell : sulfur and sulfides Magnetism – magnetite Fizz in dilute HCl acid : calcite
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Mineral Identification
Appearance – color and overall appearance Calcite and Hematite look dramatically different
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Mineral Identification
Hardness A measure of how easily a mineral can be scratched Talc is so soft you can scratch it with your fingernail Diamond is the hardest mineral Mohs scale List of common minerals to compare hardness (see table 1) Each mineral is given a value from 1 (softest) to 10 (hardest)
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Mineral Identification
Luster – the way a mineral reflects light Can be metallic or non-metallic Metallic minerals shine like metal Ex: graphite, pyrite Non-metallic metals are usually said to be dull, silky or glassy Ex: quartx, halite, flourite
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Mineral Identification
Specific Gravity – ratio of its weight compared to the weight of an equal volume of water You can compare the specific gravity of two minerals by holding samples of equal size mineral in each of your hands Ex: Gold 17 (17 X heavier than water), pyrite 5 (5 X heavier than water)
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Mineral Identification
Streak – when a mineral is rubbed across a piece of unglazed porcelain tile, a streak of powdered mineral is left behind Streak is the color of the mineral in powdered form Minerals must be softer than the streak plate for this test to work
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Mineral Identification
Cleavage and fracture – the way a mineral breaks
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Cleavage Minerals that break along smooth flat lines have cleavage
Ex: Mica
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Fracture Minerals that break along uneven, jagged surfaces have fracture Ex: Quartz
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Mineral Identification
Other properties Magnetism – magnetite picks up iron shavings HCl test – causes fizzing bubbles on calcite Double images – calcite causes light to form double images
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Math Problem 1. GRAB A CALCULATOR. (YOU WON'T BE ABLE TO DO THIS ONE IN YOUR HEAD) 2. KEY IN THE FIRST THREE DIGITS OF YOUR PHONE NUMBER (NOT THE AREA CODE) 3. MULTIPLY BY 80 4. ADD 1 5. MULTIPLY BY 250 6. ADD THE LAST 4 DIGITS OF YOUR P HONE NUMBER 7. ADD THE LAST 4 DIGITS OF YOUR PHONE NUMBER AGAIN. 8. SUBTRACT 250 9. DIVIDE NUMBER BY 2 DO YOU RECOGNIZE THE ANSWER? What is it????
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Mineral Uses Gems Rare and beautiful Cullinan Diamond
Found in S. Africa 3,106 carats Great Star of Africa Hope Blue Diamond Famous for bringing the owner bad luck
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Mineral Uses Diamonds are often used as cutting tools
Rubies are used to produce laser lights Quartz crystals are used to create watches
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Useful Elements in Minerals
Ores – a mineral is an ore if it contains a useful substance that can me mined for profit Iron Titanium Used in golf clubs, jewelry, watches, racing bicycles
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