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.