Azurite, (on Anglesite)

Chemistry: Cu3(CO3)2(OH)2
Size: 170 mm
Owner: Harvard University (Karabacek Collection)
Photographer: Malcolm Southwood

The matrix to this remarkable specimen is a group of large, white, opaque and striated anglesite crystals (to 120 mm). Growing around the margin of one of these anglesite crystals is a tiara-like arc of well-formed, lustrous, blue-black azurite crystals (to 38 mm). Localised dustings and partial crusts of arsentsumebite clearly post-date the larger azurite crystals, but are themselves supplanted by a sprinkling of tiny (sub-mm) bright royal-blue azurites.

The paragenesis therefore appears to be:  anglesite >> azurite (1) >> arsntsumebite >> azurite (2)

This specimen is from the Karabacek Collection (#2068; Harvard University number MGMH 93649), which dates it to the first oxidation zone. 

(FOV for Photograph 2 is 90 mm.)

Courtesy  of  the  Mineralogical  &  Geological  Museum  at  Harvard  University,  Azurite; MGMH  ID# 93649, Tsumeb; Namibia. @ copyright 2012, President and Fellows of Harvard College. All rights reserved.