Franckeite

Formula	Pb21.7Sn9.3Fe4.0Sb8.1S56.9
Origin	Chocaya Mine, Potosi (Bolivia)
Description	a spherical aggregate of Franckeit crystals
Classification (Lapis)	Sulfides
Crystal System	Triclinic
Hardness	2,5 – 3,0
Colour	Grayish black
Streak	Grayish black
Luminescence	none observed
Lustre	Metallic
Transparency (Opacity)	Opaque
Cleavage	Perfect
Fracture
Magnetism	no
Geological Setting	In hydrothermal Ag-Sn deposits; in a limestone contact metamorphic deposit
Specific Gravity	8,98 g/cm3