Book 27, Question 80
How does a mineral's shine help you name it?
Luster describes how a mineral looks when light bounces off its surface.
Metallic luster shines like metal, as in pyrite. Glassy luster looks like glass, as in quartz. Others look pearly, silky, waxy, or dull and earthy. Luster is one of the first clues rock detectives use, because you can notice it without any tools. Try tilting a stone under a lamp to see how the light moves.