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Andyrobertsite, (Holotype Specimen)


Chemistry: KCdCu5(AsO4)4[As(OH)2O2].2H2O
Size: 41 mm
Owner: W.W. (Bill) Pinch
Photographer: John Schneider

An electric-blue, pyramid-shaped aggregate (18 mm high) of platy crystals comprising lamellar intergrowths of andyrobertsite and calcioandyrobertsite. This iconic specimen is the holotype for both of these minerals. The matrix consists of cuprian adamite, with zincolivenite. (FOV for the main photograph is 30 mm.)

The specimen is believed to have been found by Tsumeb miner Richard Baughart, in the early 1950s. It was sold in September, 1996, as "keyite" to its current owner, who recognised that it clearly was not keyite! 

Andyrobertsite and calcioandyrobertsite were subsequently described as new minerals for which Tsumeb is the type locality (Cooper et al., 1996)