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Franckeite, chemical
formula Pb5Sn3Sb2S14,
belongs to a family of complex
sulfide
minerals. Franckeite is a
sulfosalt. It is closely
related to
cylindrite. It is named after
the mining engineers, Carl and
Ernest Francke. It can be found in
Bolivia at Poopo in Oruro and at
Las Aminas, southeast of Chocaya,
in Potosi. It was discovered in
1893. Franckeite has an average
density of 5.7 and can be both
grayish black, blackish gray in
color.
