“6.5 x 5.0 x 4.0 cm. This is an excellent combination specimen of well-formed, lustrous diaphorite crystals intergrown with a rich amount of rare, superb quality, crystallized franckeite. The metallic diaphorite has sharp, visibly exposed crystals up to 8 mm, and embedded crystals up to 1.8 cm. Both minerals are sulfosalts with lead and tin, with the diaphorite having silver and the franckeite having iron. This comes with a label that states that it was mined in 1939 by Federico Ahlfeld, and formerly in the collection of Richard Kosnar. Although some of his labels must be taken carefully for the added information, it is well known that he obtained from his long Bolivian sources a good portion of specimens from the Ahlfeld collection, so this could indeed be true. Certainly, this is an old piece and must be among the finest diaphorite combination pieces from South America (at least, that I am aware of). Ex. Hoppel Collection.
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Robert Lavinsky - 9th January 2015