Chemistry: Cu3(CO3)2(OH)2
Size: 140 mm
Owner: Harvard University (W.Klein Collection)
Photographer: Malcolm Southwood

A very fine group of large, blue-black azurite crystals (to 95 mm) on a somewhat friable carbonate- and arsenate-rich matrix. A small sample removed from the matrix for PXRD analysis confirmed the presence of smithsonite and conichalcite. There is minor alteration of the azurite to malachite at the base of the crystals adjacent to the matrix. 

The specimen is from the Wilhelm Klein collection (# 1010) and Klein's catalogue records that it was collected from 8 Level.  It is very likely that this specimen is from the 1929 "Sam Gordon Pocket".  Gordon, visiting Tsumeb with the Fourth Vaux Expedition from the Philadelphia Academy of Natural Sciences, was forced to share his famous azurite discovery with mine manager F.W. Kegel.  The habit of these crystals is a very close match for the Gordon Pocket, and Klein and Kegel - both avid mineral collectors - are known to have exchanged specimens with one another.

Courtesy  of  the  Mineralogical  &  Geological  Museum  at  Harvard  University,  Azurite; MGMH  ID# 116495, Tsumeb; Namibia. @ copyright 2012, President and Fellows of Harvard College. All rights reserved.