Cylindrite

Cylindrite is a sulfosalt mineral containing tin, lead, antimony and iron with formula: Pb₃Sn₄FeSb₂S₁₄. It forms triclinic pinacoidal crystals which often occur as tubes or cylinders which are in fact rolled sheets. It has a black to lead grey metallic colour with a Mohs hardness of 2 to 3 and a specific gravity of 5.4.