There are two main varieties of quartz: crystalline quartz and cryptocrystalline quartz. Quartz crystals are found in cavities in geodes from granite porphyries and from granite pegmatites.
Crystalline quartz is allochromatic, meaning trace impurities will create a variety of colors. The colored varieties include amethyst (violet – purple), citrine (yellow), smoky (brown), morion (black), rose (pink), sapphire quartz (blue), and milky (semi-translucent white).
* Scientific proof may not be available to substantiate these claims.