Ettringite

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The unusual calcium aluminium sulphate hydroxide hydrate mineral Ettringite was originally described from two localities in Germany as small colourless crystals but during the 1980s a fantastic new set of finds at the N'Chwaning mines in the Kalahari Manganese Field, N. Cape Province, South Africa produced exceptionally large, and colourful sulphur-yellow prismatic crystals. This miniature specimen from the N'Chwaning mines comes from the Hettrich Collection in Germany and features clusters of rich deep yellow-coloured stocky prismatic Ettringite crystals displaying sloping shallow pyramidal terminations, but unusually with the sloping termination set-back slightly inside the edges of the prism sides. Sat on a layer of finely crystallized Quartz, the largest Ettringite crystal is 1.1 cm in length but is missing one side of its termination. The smaller, perfectly terminated crystals reach up to 5 mm in length and some have extremely glassy terminations.