Usually, we notice the color of a mineral first. Some minerals are easily identified by color because they are never any other color. For example, malachite is always green. Keep in mind, however, that color by itself isn't enough to identify a mineral. Chemical impurities can change the color of a mineral without changing its basic make-up. For example, quartz in its purest form is colorless and clear as glass. Quartz with traces of iron becomes violet (amethyst). With traces of manganese, it turns pink (rose quartz). If quartz is exposed to radiation, it turns brown (smoky quartz).