Color is a fairly reliable indicator in the opaque and metallic minerals—for instance the blue of the opaque mineral lazurite or the brass-yellow of the metallic mineral pyrite.
In the translucent or transparent minerals, color is usually the result of a chemical impurity and should not be the only thing you use. For instance, pure quartz is clear or white, but quartz can have many other colors.
Try to be precise with color. Is it a pale or deep shade? Does it resemble the color of another common object, like bricks or blueberries? Is it even or mottled? Is there one pure color or a range of shades?
If you have an ultraviolet light, this is the time to see if the mineral has a fluorescent color. Make note if it displays any other special optical effects.
