Lautite from Lauta, Marienberg, Germany — Photo: Kritzolina · CC BY-SA 4.0
Lautite
A rare orthorhombic copper-arsenic sulfide forming prismatic crystals up to 2.3 cm.
Intro adapted from Wikipedia (CC BY-SA).
Lautite is an IMA-recognized mineral species in the sulfosalt class, with the chemical formula CuAsS.
It crystallizes in the orthorhombic crystal system (space group Pnma).
Key properties: Mohs hardness 3–3.5; specific gravity 4.91; Black streak; Metallic to semimetallic luster.
IMA symbol Ltt, grandfathered status — known before the IMA’s founding, named in 1881.
Found in hydrothermal veins formed at medium temperatures.
It is found associated with Arsenic, tennantite, proustite, chalcopyrite, galena, barite (Lauta, Germany); kutı́naite, paxite (Niederbeerbach, Germany); arsenic, bismuth, tennantite.
The name refers to the Lauta, Germany occurrence.