Quartz

specimen number:
2292375

location:
Boekenhouthoek, Mkobola, Mpumalanga, South Africa

description:
A grouping of attractive light purple quartz crystals, this showing multiple generations of crystallization. Many call this material cactus quartz. This is the variety of the species known as amethyst. In good condition all around.

The Boekenhouthoek area, situated in the Mkobola district of Mpumalanga, South Africa, is the primary source of cactus quartz, also known as spirit quartz. Geologically, these formations occurred within crevices of Precambrian granite dated to approximately 2.3 billion years ago. The crystal habit formed in two distinct hydrothermal phases: first, silica-rich solutions crystallized to form large, central quartz crystals, often colored purple by trace iron to form amethyst. Later, a second influx of silica-rich fluids under different temperature and pressure conditions deposited hundreds of tiny, secondary quartz crystals that grew outward along the sides of the main crystal shafts, creating a spiky, cactus-like appearance. Historically, a local resident first discovered the specimens in 1986 while digging a house foundation. Early commercial collectors falsely reported the origin as the Magaliesberg Mountains to protect the secret location from local excavation restrictions, but by the early 2000s, the true locality was identified as independent local mining expanded.

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