Lorándite is a thallium with the chemical formula: TlAsS2. Though rare, it is the most common thallium-bearing mineral. Lorandite occurs in low-temperature hydrothermal associations and in gold deposits. Associated minerals include stibnite , realgar, greigite , tetrahedrite and barite
The mineral is being used for detection of solar neutrino via a certain nuclear reaction It has a monoclinic crystal structure consisting of spiral chains of AsS3 tetrahedra interconnected by thallium atoms, and can be synthesized in the laboratory.