What is Lorándite?
Lorándite is a rare thallium arsenic sulfide with deep red colour and high density, found in specialised hydrothermal ore environments.
Mineralogy and crystal structure
Reference formula: TlAsS2. Lorándite is a monoclinic thallium arsenic sulfide. Its thallium and arsenic content makes it a mineralogical reference and ore-mineral specimen rather than a handling stone; the selected COD entry provides a verified structural model. Lorándite is classified with sulfosalts and has a monoclinic crystal system. Typical hardness is 2–2.5 on the Mohs scale and specific gravity is approximately 5.9–6.0.
Colour, lustre and habit
Typical colours include scarlet, red, orange-red, black-red. The usual prismatic, tabular, granular habit and adamantine, resinous, metallic lustre help describe a specimen, but colour alone is not diagnostic.
Formation and notable localities
Lorándite forms in or is associated with low-temperature hydrothermal veins and arsenic-antimony-thallium ore deposits. Important documented localities include Macedonia, Bulgaria, Turkey, Hungary and the United States.
A red sulfosalt for the specialist cabinet
Lorándite is a collector mineral for people who value rare chemistry as much as appearance. Its red to black-red colour and extraordinary density stand out in a sulfosalt suite, especially when the hydrothermal locality is documented.
Collecting and care
Highly toxic thallium- and arsenic-bearing ore: keep sealed, avoid dust and skin contact, never cut or grind, and wash hands after handling.
