Summary: Characters of Teallite:—
Grey-black colour, metallic lustre, soils paper like graphite, occurs in flexible folia with nearly square outline, perfect basal cleavage, hardness, 1–2, does not scratch gypsum, density, 6·36. Orthorhombic, a:b:r = 0·93 : 1 : 1·31. Chemical formula, PbSnS2.
Probable chemical formula of franckeite:— Pb5FeSn3Sb2S14 = 3PbSnS2 + Pb2FeSb2S8.
Probable chemical formula of cylindrite:— Pb3FeSn4Sb2S14 = 3PbSnS2 + SnFeSb2S8.