Cactus Quartz, or Spirit Quartz, was first discovered in 1986 in the Magaliesberg Mountain Range near Pretoria, South Africa.  It was called "Spirit Quartz" by the South African tribal medicine men who used them for healing rituals.  Cactus quartz is formed by a quartz or amethyst crystal being encrusted by a second generation of smaller crystals grown on its faces.  It occurs as quartz, citrine and amethyst, and comes in a wide range of colors, including purple amethyst, violet amethyst, smoky, milky clear and golden citrine.