jamesonite

Jamesonite is a lead iron antimony sulfide mineral with the chemical formula Pb4FeSb6S14. It is a member of the sulfosalt group. Jamesonite typically occurs as needle-like or prismatic crystals, often in radiating aggregates or as fibrous masses. Its color is steel-gray to black, and it possesses a metallic luster. The hardness of jamesonite on the Mohs scale is between 2 and 3, making it a relatively soft mineral. Its specific gravity is around 5.6.

Jamesonite is found in hydrothermal veins, typically associated with other sulfide minerals such as galena, sphalerite, and pyrite. It is often found in mesothermal to epithermal deposits. Notable occurrences include those in the United States (especially in Montana and Idaho), Mexico, Peru, and various European countries like the Czech Republic and Romania.

Due to its lead and antimony content, jamesonite can be a source mineral for these elements, though it is not a primary ore mineral for either. It is primarily of interest to mineral collectors for its distinctive crystalline habits and association with other valuable ore minerals. The mineral was first described in 1837 and named in honor of Robert Jameson, an English mineralogist.