How Are Minerals Identified?How Are Minerals Identified? ColorColor LusterLuster HardnessHardness StreakStreak DensityDensity Crystal ShapeCrystal Shape Cleavage and FractureCleavage and Fracture Special Properties, Special Properties, such as such as

magnetism, smell, taste and radioactivitymagnetism, smell, taste and radioactivity

Minerals are identified by their properties.Minerals are identified by their properties.

ColorColor Usually the first and most easily observedUsually the first and most easily observed

QUARTZROSE QUARTZ SMOKY QUARTZ

- Some minerals are the same color as others- Some minerals are the same color as others- Some minerals can have many colors- Some minerals can have many colors

Not a reliable way to identify a mineralNot a reliable way to identify a mineral

LusterLuster General appearance of a mineral General appearance of a mineral

surface in reflected lightsurface in reflected light

Glassy-Obsidian

Examples of lusterExamples of luster Metallic

Greasy: resembles the way petroleum jelly or a greasy surface reflects light

Silky: resembles the way silk reflects light Earthy: dull, may be rough or dusty Waxy Adamantine: resembles the way a diamond shines

Vitreous: similar to glass Resinous: resembles the way plastic reflects light Pearly: resembles the way pearls shine

Pitchy – looks like tar Fibrous – looks like fibers

HardnessHardness Resistance to scratching by different Resistance to scratching by different

items; “scratchability”items; “scratchability” Mohs Hardness Scale is used to determine Mohs Hardness Scale is used to determine

the hardness of minerals by comparing the hardness of minerals by comparing them to substances of known hardness:them to substances of known hardness:

< < 22 fingernail fingernail 33 penny penny ~ 5~ 5 Steel of a pocket Steel of a pocket

knife knife 5.55.5 Window GlassWindow Glass 6.66.6 Steel of a file Steel of a file 77 Quartz crystal Quartz crystal

Mohs Mineral Hardness Mohs Mineral Hardness ScaleScale

1) Talc 1) Talc 2) Gypsum 2) Gypsum 3) Calcite 3) Calcite 4) Flourite 4) Flourite 5) Apatite 5) Apatite 6) Feldspar 6) Feldspar 7) Quartz 7) Quartz 8) Topaz 8) Topaz 9) 9)

Corundum Corundum 10) Diamond10) Diamond

Softest

Hardest

1

2

3

4

5

6

7

8

9

10

StreakStreak The color of a finely powdered mineral The color of a finely powdered mineral Determined by rubbing the mineral on a Determined by rubbing the mineral on a

piece of unglazed porcelain (streak plate)piece of unglazed porcelain (streak plate)

DensityDensity The amount of matter in a given space The amount of matter in a given space

Specific Gravity is the comparison of a Specific Gravity is the comparison of a substance’s density to the density of watersubstance’s density to the density of water

Crystal ShapeCrystal Shape Minerals have a Minerals have a

characteristic crystal characteristic crystal shape resulting from shape resulting from the atomic packing of the atomic packing of the atoms when the the atoms when the mineral is formingmineral is forming

Cleavage and FractureCleavage and Fracture CleavageCleavage is the tendency of a is the tendency of a

mineral to split or crack along mineral to split or crack along parallel or flat planes.parallel or flat planes.

BIOTITE QUARTZ Obsidian

No Cleavage 1 Direction of Cleavage

Conchoidal Fracture

FractureFracture occurs when a mineral occurs when a mineral breaks at random lines instead of at breaks at random lines instead of at consistent cleavage planes.consistent cleavage planes.

Fracture

Special Special PropertiesProperties Magnetism (Magnetite)Magnetism (Magnetite)

Taste (Halite)Taste (Halite) Smell (Sulfur)Smell (Sulfur) Reaction to HCl (Calcite)Reaction to HCl (Calcite) Double refractive - Double refractive - a thin, clear a thin, clear

piece of calcite placed over an piece of calcite placed over an image will cause a double imageimage will cause a double image

Radioactivity - minerals containing radium or Radioactivity - minerals containing radium or uranium can be detected by a Geiger counteruranium can be detected by a Geiger counter

Glowing under ultraviolet light (Fluorite)Glowing under ultraviolet light (Fluorite)

Economic Importance of Economic Importance of MineralsMinerals

Minerals are in many things we see Minerals are in many things we see and use everyday such as; bricks, and use everyday such as; bricks, glass, cement, plaster, iron, goldglass, cement, plaster, iron, gold

Every American Requires Every American Requires 40,000 Pounds of New Minerals 40,000 Pounds of New Minerals

per Yearper YearAt this level of consumption the average newborn infant At this level of consumption the average newborn infant will need a lifetime supply of:will need a lifetime supply of:- 795 lbs of lead (car batteries, electric components)- 795 lbs of lead (car batteries, electric components)- 757 lbs of zinc (to make brass, rubber, paints)- 757 lbs of zinc (to make brass, rubber, paints)- 1500 lbs of copper (electrical motors, wirings- 1500 lbs of copper (electrical motors, wirings- 3593 lbs aluminum (soda cans, aircraft)- 3593 lbs aluminum (soda cans, aircraft)- 32,700 lbs of iron (kitchen utensils, automobiles, - 32,700 lbs of iron (kitchen utensils, automobiles, buildings)buildings)- 28,213 lbs of salt (cooking, detergents)- 28,213 lbs of salt (cooking, detergents)- 1,238,101 lbs of stone, sand, gravel, cement (roads, - 1,238,101 lbs of stone, sand, gravel, cement (roads, homes)homes)