1. Identifying Minerals 4.2

2. Characteristics of Minerals – for identification
A. Color – often caused by presence of trace elements or compounds.
Least reliable
More than one mineral may have the same color.
Luster - the way light is reflected from the surface of the mineral.
1. Metallic/Nonmetallic
2. Dull
3. Pearly
4. Waxy, glassy, silky

3. 1. How a mineral feels to the touch.
Texture
1. How a mineral feels to the touch.
2. Smooth, rough, ragged, greasy, soapy, glassy
Streak – powder left when mineral is rubbed against unglazed porcelain.
1. Color of streak aids in identification.
2. Can only be used with minerals SOFTER than the porcelain.
Foliated Texture

4. Hardness – measure of how easily a mineral can be scratched.
1. Mohs scale of Hardness uses reference numbers 1  10.
soft hard
2. Talc is softest
3. Diamond is hardest
Cleavage and Fracture – pattern of breaking
1. Cleavage – smooth flat planes of breakage.
2. Fracture – rough and/or jagged breaks.
Fractured surface

5. G. Density – M/V (mass divided by volume).
1. Always the same for a specific mineral.
2. Units in g/ml or g/cm3.
3. Specific Gravity
a. Most common measure of density used by geologists.
b. Ratio of weight of a substance to the weight of an equal volume of water at 40C.
H. Special Properties
1. Double Refraction – see two images when look through the mineral
2. Reaction with acid – fizz or odor.
3. Magnetic – acts like a magnet.
Click in box to play movie
Magnetite

6. Mineral Uses
Ores – a mineral is an ore if it contains a useful substance that can be mined at a PROFIT.
1. Hematite – ore for iron
2. Bauxite – ore for alumimum.
B. Mines – where ores are obtained.
1. Open Pit – near surface.
2. Underground
Gems – valuable minerals prized for rarity and beauty.
1. Trace minerals can make the difference.
2. Amethyst = gem form of quartz.
Click in box to play movie.

7. Review
Click in box to play movie

8. Citations
Rocks and Minerals: The Hard Facts. Rainbow Educational Media unitedstreaming. 11 July
How to Identify Minerals. Discovery Channel School unitedstreaming. 11 July
Minerals and Ores. United Learning unitedstreaming. 11 July
outernode.pir.sa.gov.au/minerals/education/te...
socrates.berkeley.edu/~eps2/wisc/Lect7.html
csmres.jmu.edu/.../fichter/Minerals/luster.html
geology.csupomona.edu/alert/mineral/streak.htm
geology.csupomona.edu/alert/mineral/cleavage.htm
upload.wikimedia.org/wikipedia/commons/thumb/d/d4/Magnetite-usa51d.jpg/220px-Magnetite-usa51d.jpg