Ettringite is a rare calcium aluminium sulphate hydroxide hydrate usually seen in small colourless crystals, but discoveries at the N'Chwaning mines in the Kalahari Manganese Field, South Africa during the 1980s and 1990s produced something very different, and very much more spectacular - larger yellow crystals. This interesting specimen features very many bright, sulphur-yellow hexagonal prismatic Ettringite crystals with prominent sloping pyramidal terminal faces truncated by a pinacoid face. These crystals sit across small (to 1.8 cm in length) terminated colourless Quartz crystals lining a cavity in Quartz-dominated matrix, but with tiny snow-white silky spherical sprays throughout. The smaller Ettringite crystals are exquisite, but several of the larger crystals are damaged, but these expose an unusually sharp transition to a chalky-white centre to the crystals. The Ettringite crystals range from 9 mm down to 1 mm in length. Ex Hettrich Collection.
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