Lorándite
| Lorándite | |
|---|---|
| General | |
| Category | Sulfosalt mineral |
| Formula | TlAsS2 |
| IMA symbol | Lor |
| Strunz classification | 2.HD.05 |
| Crystal system | Monoclinic |
| Crystal class | Prismatic (2/m) (same H-M symbol) |
| Space group | P21/a |
| Identification | |
| Color | Red to carmine-red, lead gray |
| Crystal habit | Prismatic tabular striated parallel to [001] |
| Cleavage | [100] perfect, [001] distinct |
| Fracture | Conchoidal |
| Mohs scale hardness | 2.0–2.5 |
| Luster | Sub-metallic – adamantine |
| Streak | Cherry-red |
| Diaphaneity | Subtransparent |
| Specific gravity | 5.53 |
| Optical properties | Biaxial (+) |
| Refractive index | nα = 2.720 |
| Pleochroism | Weak; Y = purple-red; Z = orange-red |
| Other characteristics | Tenacity: flexible, forming cleavage lamellae and fibers |
| References | |
Lorándite is a thallium arsenic sulfosalt 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 and mercury ore deposits. Associated minerals include stibnite, realgar, orpiment, cinnabar, vrbaite, greigite, marcasite, pyrite, tetrahedrite, antimonian sphalerite, arsenic and barite.
The mineral is being used for detection of solar neutrino via a certain nuclear reaction involving thallium. It has a monoclinic crystal structure consisting of spiral chains of AsS3 tetrahedra interconnected by thallium atoms, and can be synthesized in the laboratory.