Amethyst is a popular purple-colored variety of quartz that contains manganese. It is the manganese that produces Amethyst's purple color, the iron content in the stone determines the relative darkness of the purple.
Amethyst is believed to open and activate the Crown Chakra. Do bear that Reiki and crystal healing is believed to balance energy for the purpose of pain management, stress reduction and relaxation. These treatments should not be treated as a substitute for medical or psychological care. Crystals are powerful and should be treated with respect.