MINERAL IDENTIFICATION CHAPTER 5 SECTION 3

BY INSPECTION (VISUAL) 1. COLOR – LEAST RELIABLE TEST a. VARIOUUS MINERALS HAVE THE SAME COLOR b. IMPURITIES MAY CHANGE SOME MINERALS COLOR C. SOME MINERALS CHANGE WHEN EXPOSED TO AIR CINNIBAR – REDSULFUR – YELLOW MALACHITE – GREENAZURITE - BLUE

2.LUSTER – HOW A MINERAL SURFACE REFLECTS LIGHT METALLIC – SHINY LIKE A POLISHED METAL – PYRITE AND GALENA NONMETALLIC VITREOUS – GLASSLIKE (QUARTZ) PEARLY – (MICA) RESINOUS – WAXY (SPHALERITE) ADAMANTINE – SHINY (DIAMOND)

3. CRYSTAL SHAPE - ONE OF SIX PATTERNS. RARE IN NATURE

BY TESTING: 1.STREAK – COLOR OF A POWDERED MINERAL METALLIC – AS DARK OR DARKER THAN MINERAL NONMETALLIC – USUALLY COLORLESS OR WHITE

PYRITE STREAK

2. BREAKAGE a. CLEAVAGE – TENDENCY OF A MINERAL TO BREAK ALONG A FLAT SHINY SURFACE. INDICATES ZONES OF WEAKNESS IN ATOMIC BONDS ( b. FRACTURE – UNPREDICTABLE BREAK THAT DOES NOT OCCUR ALONG ANY SURFACE CONCHOIDAL AND FIBROUS FRACTURES

CALCITE CLEAVAGE

HALITE CLEAVAGE

FRACTURES

CONCHOIDAL FRACTURE

FIBROUS FRACTURE (ASBESTOS)

3. HARDNESS – MINERALS RESISTENCE TO BEING SCRATCHED MOH’S HARDNESS SCALE 1.TALC 7. QUARTZ 10 DIAMOND

4. SPECIFIC GRAVITY – RATIO COMPARING WEIGHT OF MINERAL TO THE WEIGHT OF AN EQUAL VOLUME OF WATER Wa Wa – W H20 NONMETALLIC = 3 OR LESS METALLIC = 5 OR MORE

Specific gravity is a unit less measure, because it is derived from the density of the mineral divided by the density of water and thus all units cancel. However, since water's density equals 1 gram per cubic centimeter (at specific conditions), then a mineral's specific gravity would also correspond to a mineral's density as expressed in grams per cubic centimeter. Specific gravity, or SG, as already stated compares the density of a mineral to the density of water. If a mineral has a SG of 2, then it is twice as dense as water. If a mineral has a SG of 3 then it is three times as dense as water and so forth.

5. ACID TEST – USED TO IDENTIFY CARBONATE MINERALS. REACT BY BUBBLING – CO 2 BEING RELEASED.

6. SPECIAL PROPERTIES a. MAGNETIC – ATTRACTED TO A MAGNET (MAGNETITE), LODESTONE – ACTS LIKE A MAGNET

MAGNETITE

b. DOUBLE REFRACTION – SPLIT LIGHT CAUSING DOUBLE IMAGE (ICELANDIC SPAR CALCITE)

c. FLOURESCENT – GLOW UNDER A UV LIGHT PHOSPHORESCENCE – WILL CONTINUE TO GLOW AFTERWARD

d. TASTE – HALITE CAN BE IDENTIFIED BY IT’S SALTY TASTE