Cylindrite

Cylindrite is a rare sulfosalt mineral consisting primarily of lead, tin, and sulfur. It is classified as a lead-tin sulfide sulfosalt, with a complex and variable composition that can reflect different proportions of its constituent metals and sulfur. The mineral is most notable for its distinctive crystalline habit, which features slender, cylindrical, or needle-like crystals that can form radiating or fibrous aggregates.

In hand specimens, cylindrite typically appears with a metallic luster and a lead-gray to black color. The streak is usually gray, and the mineral tends to be relatively soft, with a Mohs hardness around the low end of the scale. Its crystals are acicular to cylindrical, giving specimens a characteristic cylindrical texture and sometimes a threaded or banded appearance.

Cylindrite forms in hydrothermal veins and tin–lead ore deposits, where it is commonly associated with minerals such as cassiterite, galena, sphalerite, and other sulfides and sulfosalts. It has been reported from several localities worldwide, but remains a relatively uncommon mineral that is valued by collectors for its unusual habit.

The name cylindrite derives from the cylindrical crystal habit that is characteristic of the mineral. Its identity as a lead-tin sulfide sulfosalt and its distinctive habit help distinguish it from other sulfide minerals in ore deposits.