calcioandyrobertsite

The type specimen for calcioandyrobertsite (and andyrobertsite) is believed to have been mined at Tsumeb in the early 1950s (Cooper et al. 1999), indicating a high probability that it is from the first oxidation zone. It originally belonged to Richard Baughart, a mining engineer working at Tsumeb and changed hands several times before being purchased by Bill Pinch at the 1996 Denver show, labelled as zinc-deficient keyite. Analysis demonstrated the presence of two new minerals, calcioandyrobertsite (IMA 1997-023) and andyrobertsite (IMA 1997-022). The crystal structure (of both minerals) was refined and solved by Cooper and Hawthorne (2000). Calcioandyroberstsite is a compositional variant of andyrobertsite, which was named to honour Andrew C. Roberts (b. 1950), mineralogist with the Geological Survey of Canada. Type material is conserved at the Royal Ontario Museum (catalogue numbers M47022 and M47110) and at the Smithsonian Institution (catalogue number NMNH 171487).

The type assemblage comprises calcioandyrobertsite (with andyrobertsite) on tennantite, with zincolivenite and olivenite (Cooper et al. 1999). On the type specimen calcioandyrobertsite and andyrobertsite occur as intimate lamellar intergrowths that are crystallographically continuous; the two species are not visually distinguishable.

andyrobertsite; chalcocite; davidlloydite; geminite; lindackerite; olivenite; stranskiite; tennantite-(Zn); zincolivenite