Zinkenite

General Information: Chemical Formula:Pb9Sb22S42 Composition:(Molecular Weight = 5,890.07 gm)Antimony 45.47 % SbLead 31.66 % PbSulfur 22.87 % S  Empirical Formula: Pb9Sb22S42 Name Origin:Named after the mineralogist, J. K. L. Zincken (1798-1862).Physical Properties: Cleavage:[1120] Imperfect Color:gray or steel gray. Density:5.12 - 5.35, Average = 5.23 Diaphaniety:Opaque Habits:Acicular - Occurs as needle-like crystals., Prismatic - Crystals Shaped like Slender Prisms (e.g. tourmaline)., Striated - Parallel lines on crystal surface or cleavage face. Hardness:3-3.5 - Calcite-Copper Penny Luminescence:None. Luster:Metallic Streak:steel grayMore details...