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Adamite


Mineral: Adamite, Malachite
Chemistry: Zn2(AsO4)(OH)
Size: 78 mm
Owner: Harvard University (Karabacek Collection)
Photographer: Malcolm Southwood

Crystals of green cuprian adamite (to 3 mm) in a vug in altered dolostone, extensively veined and stained by green and yellow-green arsenates and malachite. (FOV for Photograph 2 is 35 mm.)  This specimen is from the Karabacek Collection (#2640; Harvard University number MGMH 93856), which dates it to the first oxidation zone.

 

Karabacek labelled this specimen as “veszeleyite” and, in correspondence with Palache (dated 09/04/1935), claimed that it was the only known veszeleyite from Tsumeb.  In fact it is adamite; the specimen was analysed at Harvard and a hand-written note on the back of the Karabacek label (in English) reads “crystals are near adamite, not veszeleyite.”

 

By the standards of the Karabacek collection this is not an attractive specimen and must have been included because Karabacek believed it to be unique. It appears that pale-green members of the adamite - olivenite solid solution series were often mis-identified by early Tsumeb collectors; two specimens of cuprian adamite in the Wilhelm Klein Collection (also at Harvard) are mis-identified as "tsumebite", and this specimen from the Karabacek Collection provides another example.  Olivenite, and "zincian olivenite", on the other hand were clearly documented.  As a consequence, the abundance of adamite in the first oxidation zone is higher than some of the early collection catalogues and mineralogical accounts would imply.

Courtesy  of  the  Mineralogical  &  Geological  Museum  at  Harvard  University, Adamite; MGMH  ID# 93856, Tsumeb; Namibia. @ copyright 2012, President and Fellows of Harvard College. All rights reserved.