Minerals
May 10, 2015
Minerals
What is the difference in picture A and B? (Other than the obvious)
A B
What is a mineral?• Formed by natural processes such as
cooling magma and evaporating saltwater
• Inorganic – not made by life processes. Not alive.
• Element or a compound with definite chemical composition (structure)
• Solid and crystalline (atoms in patterns that repeat over and over again)
S.N.I.F.E.
Solid-not liquid, gas, or plasma
Naturally Occurring-Not manmadeInorganic–Not alive, never was
Fixed Composition - Same recipe everywhere, every timeElement or Compound-Not a mixture
How are minerals classified?
Minerals are grouped based on crystal
systems. This means that they are classified according to their type
of repeated crystal patterns.
How are minerals identified? (How can you tell them
apart?)•Color•Hardness•Luster•Specific
Gravity
•Streak•Breakage•Unique
properties
Color
• The appearance of color of a mineral.
• Minerals can also change colors when they react with air or water.
• Color is NOT very reliable for identifying minerals because colors can vary greatly and are not consistent.
• Streak tests are much more reliable.
HardnessHardness is determined by how easily a mineral can
be scratched.
Mohs Scale of Hardness is used to measure the hardness of a mineral
Mohs Hardness ScaleMohs Scale Hardnes
sHardness of
Common ObjectsTalc (softest) 1 Fingernail 2.5
Gypsum 2 Piece of copper 2.5-3.0
Calcite 3 Iron nail 4.5
Fluorite 4 Glass 5.5
Apatite 5 Steel file 6.5
Feldspar 6 Streak plate 7.0
Quartz 7 Flint sandpaper
Topaz 8 Spinel (rock shops)
Corundum 9 Emery sandpaper
Diamond (hardest) 10 Carborundum sandpaper
LusterThe way a mineral
reflects light (dull or shiny).
Metallic or Nonmetallic
Density
• D=M/V -g/cm3
• Is a measure of how much matter is in a given object.
Specific Gravity
The Density of the mineral in comparison to the Density of an
equal volume of water (1g/cm3).
• -Ex: Gold’s density is 19g/cm3. What is its Specific Gravity?
• SG=19g/cm3 divided by 1g/cm3
• SG=19
StreakThe color of a mineral when it is in powdered
form.
Tested by streaking the mineral across another object (object must be
harder than the mineral)
Breakage
Clevage-breaks along smooth, flat surfaces
Fracture-breaks with an uneven, rough, or jagged
surface
Unique PropertiesMany minerals have unique
characteristics that can also be used to identify the
mineral. Example-natural magnet, double refraction, odor, taste, reaction to acids,
fluorescence, etc.
Uses of Minerals• Minerals are a component of everyday life
because they are a part of everyday objects• Jewerly (gems-rare minerals)• Diamonds are used in industrial abrasives
and cutting tools• Some minerals are used to produce specific
types of laser light• Quartz is used in electronics• Minerals that contain useful substances can
be mined (Ex. Bauxite-aluminum; Ilemenite and Rutile-titanium)