Crystalline quartz in shades of purple, lilac, or mauve is called amethyst, stone traditionally worn to guard against drunkenness and to instill a sober and serious mind. The beautiful shades produces from manganese in clear quartz of pinkish lavender to deep purple.The name comes from a Greek word which translates literally as "not drunken". Amethyst is said to help one both avoid and recover from addiction to intoxicants.There is Mohs Hardness of 7 with a trigonal crystal structure. And green color amethyst crystals have been found in the Zimbabwe and Arizona and are said to get the color due to the heat of the sun. Amethyst is the Birthstone for February and associated with spirituality, wisdom, sobriety, and security.