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a dark-gray lustrous mineral, a mixed sulfide of copper, iron and tin, Cu₂FeSnS₄, used as an ore of tin

Stannite – Sulfide mineral – Cu₂FeSnS₄ – Stn – 2.CB.15a – Tetragonal – Scalenohedral (4̄2m) – I4̄2m – A = 5.4432, c = 10.7299 [Å]; Z = 2 – Steel-gray to iron-black, may tarnish blue – Rarely as pseudo-octahedral crystals also massive, granular, and disseminated – Penetration twins on {102} – Indistinct on {110} and {001} – Uneven – 4 – Metallic – Black – Opaque – 4.3 – 4.5.