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Azurite


Mineral: Azurite
Chemistry: Cu3(CO3)2(OH)2
Size: 300 mm
Owner: American Museum of Natural History (AMNH)
Photographer: AMNH

Large, prismatic and striated crystals of deep blue azurite (to 180 mm) occupying an open vug in a matrix that consists largely of tan-coloured calcite. A little malachite is present, mainly at the margins of the azurite crystals group.  The main crystals are terminated and undamaged, and of a size that is quite remarkable for the species.   

The famous "Newmont Azurite" was used by a miner to pay off a bar bill at the local Eckleben Hotel, in Tsumeb.  The specimen was on display behind the bar for some time, but was eventually rescued by the mine's general manager, Charles E. Stott. After several years, the specimen was shipped to the New York offices of Newmont (then the majority partner in the Tsumeb Corporation Limited) and eventually donated to the American Museum of Natural History in New York, where it remains on public display.  The story of its discovery and donation was described by Conklin (2016), who considered it to be "the world's finest mineral specimen".

Many, but by no means all, of the great azurite specimens from Tsumeb originated from the first oxidation zone, and it has been tacitly assumed that the Newmont Azurite must also have come from the upper levels of the mine, not least because at the time of its discovery (said to be 1952 by Conklin, 2016), mine development was only beginning to penetrate the levels that are now referred to as the second oxidation zone (i.e. below 26 Level). 

However, in 2017 a photograph of the specimen (see below left) came to light among the unpublished papers of the late Charles E. Stott, general manager at Tsumeb between 1953 and 1965.  The reverse of the photo (see below right) is marked “Foto: Geier” and dated “1962” and clearly attributes this “Group of giant azurite [crystals]” to the West 80 (W.80) stope on 28 Level.  Bruno Geier was the chief mineralogist at Tsumeb in 1962, and this is therefore almost certainly a photograph taken by him, which brings considerable credibility to the attributed level number. The original photograph has been donated by the Stott family to the American Museum of Natural History.

The photograph and its annotation provide evidence, albeit circumstantial, that the Newmont Azurite originated from the second oxidation zone at Tsumeb, and not from the upper levels of the mine as hitherto assumed.  Corroborative evidence is provided by Geier (1973/74), however, who provides a description of this famous specimen along with a monochrome photograph (similar, though not identical to the one from the Stott family archive). His description comes very clearly under the heading Die Mineralien der Tiefenoxydationszone (“The Minerals of the Deep Oxidation Zone”) which is of course, consistent with the evidence presented above.

This calls into question, however, the date of discovery, said to be 1952 by Conklin (2016).  According to Söhnge (1967) production on 24 Level only began in 1951, and it was 1957 before production started on levels 26, 28 and 30.  It seems almost impossible, therefore, that a discovery in a production stope on 28 Level could have been made before 1957 at the earliest.  Conceivably, the 1952 date recorded by Conklin (op cit.) could be a transcription error for the “1962” date recorded on the reverse of the Geier photograph? Most significantly, however, there is now compelling and corroborative evidence for a second oxidation zone origin for the Newmont Azurite. 

 

By courtesy of the American Museum of Natural History.