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Description and notes

Brian Kosnar says this: "From the amazing discovery from 2004, here is one of the finest examples of ferrokesterite in the world. Initially we thought these ferrokesterite specimens were twinned crystals of stannite. Virtually all of the pieces from the find were sold as "stannite", but it turns out that they are the much rarer dimorph, ferrokesterite. This species is truly only known from a handful of localities in the world, including the Type Locality at the Cligga Mine in Cornwall, England. The Bolivian specimens are tremendously superior to the Cornish pieces in every sense. They are notably larger with incredibly well-pronounced crystals (featuring beautiful penetration twins), and some are even associated with pyrite, zinkenite and andorite. For reference, these ferrokesterite were analyzed and confirmed by Bob Downs of the University of Arizona. Please read the full story that I wrote several years ago on these pieces, at this link here. It should be noted that the specimens from this discovery are undoubtedly the world's finest ferrokesterites, and in greatly limited supply. This specimen came out nearly fifteen years ago, and virtually nothing has come out of the ground in quite some time."

https://www.minclassics.com/post/960459024359/the-story-of-the-great-ferrokesterites