Associated minerals include stibnite, realgar, orpiment, cinnabar, vrbaite, greigite, marcasite, pyrite, tetrahedrite, antimonian sphalerite, arsenic and barite.

[5][6] It has a monoclinic crystal structure consisting of spiral chains of AsS3 tetrahedra interconnected by thallium atoms, and can be synthesized in the laboratory.

Lorándite was first discovered at the Allchar deposit, near Kavadarci (now North Macedonia) in 1894 and named after Loránd Eötvös, a prominent Hungarian physicist.

[2][4] Single crystals of lorandite can be grown from a mixture of thallium(I) nitrate (TlNO3), elemental arsenic and sulfur in concentrated aqueous solution of ammonia.

This reaction yields 205Pb isotope which has a long lifetime of 15.4 million years; it is induced not only by neutrinos, but also by other cosmic particles.