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WHAT IS A MINERAL?-NATURALLY OCCURING, INORGANIC SUBSTANCES
MINERALS ARE THE BUILDING BLOCKS OF ROCKS. YOU CAN’T HAVE A ROCK WITHOUT MINERALS
- THOUSANDS OF MINERALS HAVE BEEN IDENTIFIED, BUT ONLY ABOUT A DOZEN ARE COMMONLY FOUND
GRAPHITE AND DIAMOND ARE DIFFERENT FORMS OF THE ELEMENT CARBON
- SOME ARE CHEMICAL ELEMENTS OR COMPOUNDS
- SILICON AND OXYGEN ARE THE TWO MOST COMMON ELEMENTS IN THE EARTH’S CRUST
WAYS TO IDENTIFY A PARTICULAR MINERAL!
-MANY MINERALS HAVE A CHARACTERISTIC COLOR
EX: PYRITE “FOOLS GOLD” IS TYPICALLY A BRASSY YELLOW COLOR
-UNFORTUNTAELY, MANY CLEAR OR WHITE MINERALS ARE A VARIETY OF DIFFERENT COLORS BECAUSE OF IMPURITES… COLOR IS NOT A GOOD IDENTIFIER!
1) METALLIC LUSTER: LOOK, LIKE POLISHED METAL. LIGHT CANNOT GET THROUGH
EX: GALENA, PYRITE
- THE WAY LIGHT IS REFLECTED OFF A FRESHLY CUT SURFACE.. 2 TYPES
2) NON-METALLIC LUSTER: CAN BE SHINY, BUT DO NOT LOOK LIKE METAL.
EX: QUARTZ, SULFUR
- THE MINERAL IN POWDERED FORM
TESTING FOR STREAK:
RUB FRESH EDGE OF MINERAL ACROSS A WHITE, UNGLAZED TILE.
** SOME MINERALS LEAVE A POWDER THAT IS NOT THE SAME COLOR AS THE MINERAL
EX: PYRITE
-THE ABILITY OF A MINERAL TO SCRATCH OTHER SOLID OBJECTS
-OBJECTS THAT WE WILL SCRATCH IN ORDER TO TEST FOR HARDNESS INCLUDE….
-YOUR FINGERNAIL (SOFTEST)
-A PENNY
-A GLASS PLATE (HARDEST)
MOH’S HARDNESS SCALE:
-THIS SCALE ASSIGNS MINERALS A HARDNESS NUMBER
- IF THE MINERAL IS A “1” ON THIS SCALE, IT IS CONSIDERED TO BE ONE OF THE SOFTEST MINERALS
-IF A MINERAL IS A “10” ON THIS SCALE, IT IS CONSIDERED TO BE ONE OF THE HARDEST MINERALS
SOME MINERALS BREAK UPON FLAT SURFACES CALLED, CLEAVAGE PLANES
EX: HALITE: BREAKS INTO CUBES
BIOTITE AND MUSCOVITE: BREAK INTO SHEETS
FRACTURE: WHEN A MINERAL DOES NOT BREAK ON AN EVEN CLEAVAGE PLANE.
EX: QUARTZ( CONCHOIDAL FRACTURE)
HALITE
MICA
POTASSIUM FELDSPAR
CALCITE
QUARTZ
OLIVINE
GARNET
CRYSTAL: REGULARLY SHAPED SOLID FORMED BY AN ORDERED PATTERN OF ATOMS- MINERALS FORM CHARACTERISTICALLY SHAPED CRYSTALSEX: CALCITE AND HALITE LOOK VERY SIMILAR.
CALCITE= SQUISHED BOX CRYSTALS
HALITE= REGULAR BOX CRYSTALS
HALITE
CALCITE
DOES IT FEEL HEAVY FOR IT’S SIZE?
EX: GALENA= VERY DENSE