Moonstone belongs to the large mineral family of feldspars. Moonstone is an opalescent stone in a variety of colors but always with a silvery sheen. This iridescence is usually referred to as schiller but in moonstone it is called adularescence. Rainbow moonstone is milky white with a rainbow colored sheen. Moonstone is the most valuable form of feldspar.
Moonstone can range from colorless to blue, peach, green, pink, yellow, brown or gray with a silvery sheen.
Moonstone is mined in Brazil, Germany, India, Madagascar, Mexico, Myanmar, Sri Lanka, Tanzania and the United States.