Mineral: Azurite, Malachite
Chemistry: Cu3(CO3)2(OH)2
Size: 55 mm
Owner: Harvard University
Photographer: Malcolm Southwood

Blue-black azurite crystals in sub-parallel growth (to 50 mm) on a very pale greyish-green smithsonite, with malachite alteration distal to the matrix contact.

A photograph of this specimen is included as Figure 34 in the famous Palache and Lewis (1927) monograph on azurite crystallography; they chose this specimen to illustrate the style of alteration to malachite:

The alteration has the appearance of starting at some center and progressively attacking fresh azurite… The malachite fibers radiate from…many interfering centers…giving a confused network of interwoven, splendant fibers.  The front of the invading malachite is roughly concentric normal to the fibers.  Several darker coloured bands in the malachite may be seen surrounding the center of radiation.

The specimen was purchased from a Tsumeb miner (as part of a large collection) by Professor Charles Palache, during his visit to Tsumeb in April, 1922, which indicates that it must have originated from above 8 Level (the lower limit of mine development at the time of his visit).  (Harvard University # MGHM 87485).

Courtesy  of  the  Mineralogical  &  Geological  Museum  at  Harvard  University,  Azurite; MGMH  ID# 87485, Tsumeb; Namibia. @ copyright 2012, President and Fellows of Harvard College. All rights reserved.