MINERALS! WHAT IS A MINERAL? -NATURALLY OCCURING, INORGANIC SUBSTANCES  MINERALS ARE THE BUILDING BLOCKS OF ROCKS. YOU CAN’T HAVE A ROCK WITHOUT MINERALS

- SOME ARE CHEMICAL ELEMENTS OR COMPOUNDS - SILICON AND OXYGEN ARE THE TWO MOST COMMON ELEMENTS IN THE EARTH’S CRUST GRAPHITE AND DIAMOND ARE DIFFERENT FORMS OF THE ELEMENT CARBON - THOUSANDS OF MINERALS HAVE BEEN IDENTIFIED, BUT ONLY ABOUT A DOZEN ARE COMMONLY FOUND

WAYS TO IDENTIFY A PARTICULAR MINERAL! 1) COLOR 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!

2) L U S T E R - THE WAY LIGHT IS REFLECTED OFF A FRESHLY CUT SURFACE.. 2 TYPES 1) METALLIC LUSTER: LOOK, LIKE POLISHED METAL. LIGHT CANNOT GET THROUGH EX: GALENA, PYRITE

2) NON-METALLIC LUSTER: CAN BE SHINY, BUT DO NOT LOOK LIKE METAL. EX: QUARTZ, SULFUR

3) STREAK - 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

4) HARDNESS -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

5) CLEAVAGE 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)

CLEAVAGE POTASSIUM FELDSPAR HALITE CALCITE MICA

FRACTURE QUARTZ OLIVINE GARNET

6) CRYSTAL STRUCTURE CRYSTAL: REGULARLY SHAPED SOLID FORMED BY AN ORDERED PATTERN OF ATOMS - MINERALS FORM CHARACTERISTICALLY SHAPED CRYSTALS EX: CALCITE AND HALITE LOOK VERY SIMILAR. CALCITE= SQUISHED BOX CRYSTALS HALITE= REGULAR BOX CRYSTALS

HALITE

CALCITE

7) DENSITY DOES IT FEEL HEAVY FOR IT’S SIZE? EX: GALENA= VERY DENSE