Identifying Minerals 4.2

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

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

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

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

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.

Review Click in box to play movie

Citations Rocks and Minerals: The Hard Facts. Rainbow Educational Media. 1987. unitedstreaming. 11 July 2008 http://streaming.discoveryeducation.com/   How to Identify Minerals. Discovery Channel School. 2004. unitedstreaming. 11 July 2008 http://streaming.discoveryeducation.com/ Minerals and Ores. United Learning. 2003. unitedstreaming. 11 July 2008 http://streaming.discoveryeducation.com/ 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