MINERALS ARE MADE UP OF SINGLE ELEMENTS
OR COMPOUNDS
ELEMENTS A SUBSTANCE THAT CANNOT BE
BROKEN DOWN TO ANY SIMPLER
SUBSTANCE
EIGHT MOST COMMON ELEMENTS IN THE EARTH’S CRUST:
1.) OXYGEN 46%
3-8.)THE REMAINING 25% IS
COMPOSED OF Al, Fe, Ca, Na, K, Mg
2.) SILICON 29%
A MINERAL IS:
1.) NATURALLY OCCURRING
2.) DEFINITE CHEMICAL COMPOSITION
3.) INORGANIC SOLID
4.) CRYSTALLINE STRUCTURE
5.) DEFINITE SET OF CHEMICAL AND PHYSICAL
PROPERTIES
FAMILIES OF MINERALS
Native Minerals ARE COMPOSED OF SINGLE ELEMENTS.
Au (aurum)
GOLD
Ag (argentium) SILVER
Cu (cuprum)
COPPER
S
SULFUR
C
GRAPHITE OR DIAMOND
MOST MINERALS ARE COMPOSED OF TWO
OR MORE ELEMENTS
HALITE (NaCl)
QUARTZ (SiO2)
• OXYGEN AND SILICON COMBINE READILY WITH
EACH OTHER AND WITH OTHER ELEMENTS TO
FORM THIS FAMILY OF MINERALS
• MOST COMMON FAMILY OF MINERALS AND MAKE
UP OVER 90% OF ALL MINERALS
• THIS IS BECAUSE OXYGEN AND SILICON ARE THE
MOST COMMON ELEMENTS IN THE EARTH’S CRUST
* ANY MINERAL WHICH IS A SILICATE MUST
CONTAIN Si (SILICON) AND O (OXYGEN) IN THEIR
CHEMICAL FORMULA
NOW CIRCLE ALL OF THE MINERALS ON
YOUR NOTESHEET WHICH ARE SILICATES
ORTHOCLASE
AUGITE
QUARTZ
OLIVINE
BIOTITE
THE PHYSICAL PROPERTIES OF MINERALS
ARE A REFLECTION OF THE INTERNAL
ARRANGEMENT OF THEIR ATOMS
LEAST USEFUL PROPERTY, CHANGE IN THE
CHEMICAL FORMULA WILL VARY THE COLOR
OF THE MINERAL. (QUARTZ)
SiO2
CRYSTAL QUARTZ
ROSE QUARTZ
CONTAINS TITANIUM OXIDE AND MANGANESE
OXIDE TO MAKE A ROSE COLOR
- THE WAY A MINERAL SHINES IN REFLECTED LIGHT.
METALLIC-
LOOKS LIKE METAL IN THE
WAY THE MINERAL REFLECTS LIGHT
(GALENA OR PYRITE)
NON-METALLIC-
DOES NOT LOOK LIKE
POLISHED METAL, SO OTHER TERMS ARE USED
 VITREOUS- SHINY,
GLASSLIKE (QUARTZ)
• PEARLY LOOKS LIKE
PEARLS WHEN LIGHT IS
REFLECTED OFF OF THE
SURFACE (OPAL)
 WAXY- DULL SHINE LIKE
CANDLE WAX
(SULFUR, OLIVINE)
 EARTHY- NO SHINE AT ALL
(BAUXITE)
 ADAMANTINE- BRILLIANT GLOW, BEAM
OF LIGHT AT A CERTAIN ANGLE (DIAMOND)
THE COLOR OF A MINERALS POWDER
HOW DO YOU FIND THE STREAK
COLOR OF A MINERAL?
RUB THE MINERAL AGAINST A STREAK PLATE
AND OBSERVE THE POWDER’S COLOR
CLEAVAGE- TENDENCY OF A MINERAL TO
SEPARATE ALONG PLANES OF WEAKNESS
 ONE PLANE OF WEAKNESS
BASAL CLEAVAGE (MICA)
 TWO PLANES OF CLEAVAGE AT
90* (ORTHOCLASE)
 THREE PLANES OF WEAKNESS AT 90* = CUBIC (HALITE)
 THREE PLANES NOT AT 90* = RHOMBOHEDRAL (CALCITE)
FRACTURE- NO PLANES OF WEAKNESS SO THE
MINERAL BREAKS ALONG IRREGULAR SURFACES
CONCHOIDAL- SURFACES ARE SOMEWHAT
ROUNDED, SHELL-LIKE (QUARTZ)
UNEVEN- ROUGH SURFACE, NO DISTINGUISHABLE
PATTERN
 FIBROUS- JAGGED SURFACE LIKE FIBERS (WOLLASTONITE)
RESISTANCE TO BE SCRATCHED; IS VERY USEFUL
SINCE A MINERAL’S HARDNESS IS CONSTANT
• SCALE TO MEASURE HARDNESS WAS DEVELOPED
BY FRIEDRICH MOH IN 1812
• HARDNESS IS MEASURED ON A SCALE
FROM 1 BEING THE LOWEST TO 10 BEING
THE HIGHEST.
• TO DETERMINE THE HARDNESS OF A MINERAL
YOU MUST TRY TO SCRATCH THE MINERAL
AGAINST A GLASS PLATE
MINERAL NAME
1
TALC
GYPSUM
2
FINGERNAIL IS A 2.5
CALCITE
3
TYPICAL USES
TALCUM POWDER, BABY POWDER
BUILDING MATERIALS (SHEETROCK)
CEMENTS
FLUORITE
TOOTHPASTE
APATITE
FERTILIZER
FELDSPAR
FLOOR TILES
7
QUARTZ
WATCHES, ABRASIVES
8
TOPAZ
GEMSTONES (EMERALD)
9
CORUNDUM
GEMSTONES (RUBY & SAPHIRE)
10
DIAMOND
4
5
GLASS IS A 5.5
6
SAW BLADES, “AGIRL’S BEST FRIEND”
• MAGNETIC – THE ABILITY TO ATTRACT A
MAGNET (MAGNETITE)
• EFFERVESCENCE – ADDING HCL TO A MINERAL
CAUSES IT TO FIZZ
• TASTE – HALITE
• ODOR – SOMETIMES THE POWDER OF A MINERAL
HAS A CERTAIN ODOR (SULFUR SMELLS LIKE
ROTTEN EGGS)
• DOUBLE REFRACTION – SPLITS LIGHT RAYS
(CALCITE)
• FLUORESCENCE – THE ABILITY TO GLOW
UNDER ULTRA VIOLET LIGHT (SPHALERITE)
• SPECIFIC GRAVITY (DENSITY) – SOME
MINERALS HAVE ATOMS VERY TIGHTLY
PACKED, AND FEEL HEAVIER BECAUSE THEY
ARE MORE DENSE (GALENA)