You can identify minerals by the luster or way the light bounces off their surfaces. Shiny minerals have a(n) metallic luster. Another way to tell minerals apart is by observing color on a fresh surface. You tell gold from pyrite by using a streak plate. Hardness, or how well a mineral resists scratching, is measured by Moh’s scale. The hardest mineral is a(n) diamond. If a mineral has cleavage, it will break along flat surfaces. If it has fracture, it wouldn’t break smoothly.