Calcite with Duftite

Unknown Owner

Duftite is a rare lead copper arsenate hydroxide species described first from Tsumeb mine in 1920 and named in honour of Gustav Bernhard Duft, second General Manager at the mine. Although not common at Tsumeb mine it is most frequently seen in association with Calcite with which it forms as inclusions and overgrowths, sometimes producing spectacularly zoned crystals. This cabinet-sized display specimen displays the zoning extremely well, as overgrowth - the camouflage-green Duftite microcrystals growing selectively upon certain Calcite crystal faces, particularly on the trigonal summit of the crystals and down the three edges. Intriguingly, some of the Duftite-free Calcite crystal faces appear to continued to grow outwards after deposition leading to the Duftite on recessed faces. The size of this specimen is impressive, with a firm solid Calcite base, and makes it perfect for display. It has the benefit of no obvious damage and the complexity of the zonation/overgrowth makes for an interesting talking point. This style of Duftite-Calcite combination is usually seen in older material.