Arsentsumebite, (Type Specimen)

Mineral: Arsentsumebite
Chemistry: Pb2Cu(AsO4)(SO4)(OH)
Size: 32 mm
Owner: Harvard University
Photographer: Malcolm Southwood

The holotype for arsentsumebite; (unfortunately a poor photograph of a significant specimen). 

Arsentsumebite has a confused history.  It was first described by Vésignié (1935), who chanced on the correct formula, but was actually working with a mixture of duftite and bayldonite.  Bideaux et al. (1966) described the species in its own right, and deposited this specimen at Harvard University (MGHM # 134586).

We tend to think of arsentsumebite as primarily a first oxidation zone species. However, the notes written (by Harvard curator Dr Carl Francis) on the label that accompanies this specimen (see images below) suggest, albeit inconclusively, that the type specimen may be from the second oxidation zone.


Courtesy  of  the  Mineralogical  &  Geological  Museum  at  Harvard  UniversityArsentsumebite; MGMH  ID# 134586, Tsumeb; Namibia. @ copyright 2012, President and Fellows of Harvard College. All rights reserved.