LUSTER
Luster describes the appearance of a mineral when light is reflected
from its surface.
The two general divisions are metallic
(opaque and shiny – looks like “metal”) and non-metallic
(non-opaque and can be of almost any color).
Many minerals with metallic luster tarnish when exposed
to air and become dull – you must look at a fresh part.
There are several types of non-metallic luster:
Vitreous: like glass.
Dull: earthy appearance caused by
weak or diffuse reflection of light.
Pearly: like a pearl!
Greasy: as though covered
with a coat of oil or grease.
Waxy: like paraffin or candle wax/
Resinous: like resin or tree
sap.