Many minerals can turn colors due to impurities. They may also have a mottled appearance or wavy appearance.
For example, pure quartz is colorless or white, impurities can make the mineral rose, purple or pink!
Luster refers to the way a mineral shines in reflected light. Notice the difference between these two minerals?
The mineral on the left has a metallic luster, the one on the right, a nonmetallic luster.
Certain minerals have a metallic luster, such as silver, copper and gold. Minerals that do not reflect light have a nonmetallic luster, and are described by terms like glassy, pearly, dull and silky.
Other terms that might be used include greasy, dull, and earthy.
Streak of a mineral is the color of its powder when rubbed on an unglazed white tile.
The streak is often not the same color as the mineral. A minerals color may vary, but the streak rarely will!
► Moh's Hardness Scale ► HardnessMineralDescription ► 1TalcFingernail scratches it easily. ► 2GypsumFingernail scratches it. ► 3CalciteCopper penny scratches it. ► 4FluoriteSteel knife scratches it easily. ► 5ApatiteSteel knife scratches it. ► 6FeldsparSteel knife does not scratch it easily, but scratches glass. ► 7QuartzHardest common mineral. It scratches steel and glass easily. ► 8TopazHarder than any common mineral. ► 9CorundumIt scratches Topaz. ► 10DiamondIt is the hardest of all minerals.