What is Jamesonite?
Jamesonite is a lead-antimony-iron sulfosalt known for silky grey needles and sprays in hydrothermal ore veins.
Mineralogy and crystal structure
Reference formula: FePb4Sb6S14. Jamesonite has a monoclinic sulfosalt structure and commonly forms delicate acicular aggregates. Lead and antimony make it a specimen for careful display, not for casual cutting or polishing. Jamesonite is classified with sulfosalts and has a monoclinic crystal system. Typical hardness is 2–3 on the Mohs scale and specific gravity is approximately 5.5–5.7.
Colour, lustre and habit
Typical colours include steel-grey, black, lead-grey. The usual acicular, fibrous, massive habit and metallic, sub-metallic lustre help describe a specimen, but colour alone is not diagnostic.
Formation and notable localities
Jamesonite forms in or is associated with low- to medium-temperature hydrothermal veins with lead, antimony, silver and tin minerals. Important documented localities include Romania, Bolivia, Mexico, Germany, the United Kingdom, Peru and China.
The silky metallic texture collectors look for
Jamesonite is immediately recognisable at its best by a soft, steel-grey sheen and sprays of fine needles. It gives an ore collection texture as well as chemistry, especially when displayed with the quartz, sphalerite or other sulfosalts of its vein.
A mineral best read through texture
The fibrous habit has inspired aesthetic descriptions of Jamesonite as a mineral of focus and fine detail. Such language is poetic rather than scientific; the genuine fascination is its sulfosalt architecture and delicate growth habit.
Collecting and care
Lead- and antimony-bearing: keep away from food, wash hands after handling and avoid generating dust when trimming or cleaning.
