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Formula: TlAsS2
Sulphosalt, sulpharsenite,
thallium-bearing mineral
Crystal System: Monoclinic
Specific gravity: 5.53 measured and calculated
Hardness: 2 to 2½
Streak: Cherry-red
Colour: Cochineal- to carmine- red; often dark lead-grey on the surface and frequently coated by an ochre-yellow
powder
Solubility: Soluble in nitric acid, with the formation of sulphur, melts
easily
Environments
Although rare, lorándite is the most widespread thallium mineral;
it is of hydrothermal origin, typically formed at relatively low temperatures. Associated minerals include
stibnite, realgar,
orpiment, cinnabar,
vrbaite, greigite,
marcasite, pyrite,
tetrahedrite,
antimony-bearing sphalerite,
arsenic and baryte
(HOM).
Localities
At the type locality, Allchar, Rožden, Kavadarci Municipality, North Macedonia, lorándite occurs as
individual crystals 5-10 mm in size. Both tabular and prismatic, associated with
realgar
(Mindat).
Lorándite from Allchar - Image
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