Citrine "Cactus Quartz"

This is one of the really recognizable quartz varieties from Boekenhouthoek in Mpumalanga, South Africa. The area became known for its unusual “cactus quartz,” also called spirit quartz, where a larger quartz crystal gets covered by a second generation of much smaller crystals. The result is that spiky, almost cactus-like surface that makes these specimens so easy to recognize.

Boekenhouthoek has produced this material in clear, milky, amethyst, and yellow varieties. The yellow material has traditionally been sold as citrine, although some locality references note that at least some of the yellow color is actually caused by iron staining rather than true citrine.