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Published byAngelica Robbins Modified over 8 years ago
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WHAT IS A MINERAL? Chapter 3: Minerals
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A MINERAL DEFINED They are the building blocks of the crust of the Earth! Many are essential in a healthy diet. Remember the doctor always says to “take your vitamins and minerals” to stay healthy! All minerals share these 5 characteristics: Naturally occurring: mother nature makes minerals…not us! Inorganic: made of things that are not living and never will be living! Solid: hard and breakable, with the exception of mercury which is a liquid Definite chemical composition: unique combination of elements Crystalline structure: repeating pattern of atoms that creates crystals
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A MINERAL IDENTIFIED All minerals have certain traits that make them different from all the others There are 5 traits you can test to help you correctly identify a mineral sample 1. Color 2. Hardness 3. Streak 4. Cleavage/Fracture 5. Luster
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COLOR Color is okay to look at initially, but you can not base your decision only on that one trait Why? Because a lot of minerals look very much the same! If we only looked at color, we would not identify it correctly. Which of these samples is calcite and which sample is halite?
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CAN YOU SCRATCH IT? When you try to scratch a mineral, you are testing its hardness If it can be scratched, then it is softer than the object you used to scratch it If it cannot be scratched, then it is harder than the object you used to scratch it Common minerals and their hardness are ranked on Moh’s Hardness Scale, listed from the softest to the hardest
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WE HAVE A STREAKER!! The streak of a mineral is the mineral in its powdered form Minerals will only have a streak if they are softer than the streak plate (which has a hardness of 7) If the mineral has a metal in its chemical formula, it will usually leave a streak The streak color will not always be the same color as the mineral…so don’t assume!
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I NEED A BREAK!!! Cleavage and fracture are two terms used to describe how a mineral breaks Cleavage means it breaks with smooth, flat surfaces Fracture means the mineral breaks along jagged surfaces
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OH, HOW IT SHINES! How a mineral shines describes its luster If it shines like a metal, it has metallic luster If it does not shine like a metal, it has nonmetallic luster 1. Dull 2. Earthy 3. Pearly 4. Waxy
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OTHER NEAT PROPERTIES Magnetism (magnetite) Double refraction, double image (calcite) Fizzes when acid is placed on it (calcite) Fluorescence (glows under a black light) Specific gravity: THE BEST TEST TO HELP YOU IDENTIFY A MINERAL!
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