When you’re first learning mineral identification, it’s tempting to use color as the main distinguishing factor. It’s the first visual clue you perceive, and we gauge so many other things in our lives by color. However, as many know, color is hardly ever a good property for accurately identifying minerals.
Take these fluorite (CaF2) samples pictured above. Although they are all indeed fluorite, they range in color from purple, to blue, to orange, to white. Seeing as fluorite can occur in nearly every color of the rainbow, you need to be well-versed in its other properties [hardness, luster, streak, taste, cleavage, etc.] in order to identify it.
Image by author // Specimens from the American Museum of Natural History
Emily Zawacki, Ph.D. 