Clue 1 - Minerals - Station 6     Characteristic properties: Response to light
Wednesday, May 09, 2012
8:39 AM
Station 6:  Color, luster and light transmission 
How minerals look and behave under light
Musell Rock Color Chart
Since people describe colors differently, geologists use an official color chart to describe colors.  
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What is color?
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The color that you see
Color, light transmission and luster are three properties of minerals that depend on light.  The word "property" means characteristic.
Observe the color of each mineral in the "COLOR" pile.
Describe the color of each mineral in the table below.
Mineral
Types of atoms inside
Cause of unusual color
Color
Orthoclase feldspar
Potassium, aluminum,
silicon , and oxygen
Color is not unusual
Quartz 1
Silicon and oxygen
Color is not unusual
Quartz 2 
(variety aventurine)
Silicon and oxygen
Tiny mica crystals inside the quartz
Quartz 3
(variety amethyst)
Silicon and oxygen
Imperfectly arranged atoms in the quartz crystal
Observe the way that light passes through each mineral in the "LIGHT" pile.
Special terms (words) are used to describe how light passes through a mineral.  These terms describe the relative transparency of each mineral whether light passes through or not.
Match each type of transparency with a mineral.
Type of
transparency
Description of transparency
Mineral that exhibits this type of transparency
Opaque
No light passes through the mineral.
Metallic minerals are often opaque.
Transparent
Most or all light passes through the mineral  and large pieces of the mineral appears clear.
Translucent
Some light passes throughthe mineral but not all.  The mineral appears cloudy.  In a thin slice, most minerals will be more transparent,  except for those that are metallic.
Observe the luster of each mineral sample and match the luster with the sample.
Luster refers to the appearance of light reflected off the surface of a mineral.  The terms describing luster include terms such as pearly and silky.
Match each type of luster with a mineral.
Type of
luster
Description of luster
Mineral
Earthy
Dull like dirt, not shiny
Glassy
Shiny like glass
Metallic
Dull to shiny like tinfoil and other metals
Waxy
Dull shine like wax