Bayldonite ps. Mimetite with Azurite

Item Description

One of the oldest of weird and interesting classics from Tsumeb, are these shockingly green bayldonite specimens from the era of the First Oxide Zone, found in the 1890s-1910 more or less. Later, it was realized that the bayldonite "crystals" were actually crystal shapes of mimetite, and this helped to explain the phenomenon of pseudomorphs as an early example of how one species might chemically replace another and yet adopt and preserve the crystal habit of the previous species. We see this style only in very old finds from Tsumeb , and certainly cabinet sized display pieces are rare today. The specimen shows a large display face with crystals (mostly intact) of bayldonite to just over 1 cm, mixed with sparkling malachite and minor azurite. Note that the old label from the early 1900s (presumably) identified this as mimetite by the shape, although I think it also notes that they are overgrown by the bayldonite instead of replaced by it. This large piece is shockingly heavy - we were surprised when we lifted it up, and found it to be 1.3 kilos! It is solid copper and lead ore from Tsumeb, with crystallization atop! The specimen was part of a collection assembled in Zurich already by the early 1900s, and preserved intact with these gorgeous old labels until purchased by Siber and Siber in 2020. It then went into the Brent Lockhart collection.