Conichalcite

$4,500.00

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This fascinating Tsumeb specimen is both unusual geochemically and rather large considering its rarity. It comes from the generations-old Weyand Collection in Tsumeb town and although its texture appears reminiscent of the strange organic-like dendritic and floret growths of Mottramite, its colour tells a different story - a much more vibrant acidic- to lime-green than the usual khaki-, to olive-green of Mottramite. That is because the green is Conichalcite (calcium copper arsenate hydroxide) replacing, or pseudomorphing, the crystal form of earlier Mottramite (lead copper vanadate hydroxide). Small colourless Calcite crystals are scattered upon the surface, showing this later shift to calcium-rich input. The scale of this unusual specimen is impressive, as is its intactness, in superb condition and a rare survivor from this famous mine.