n. A monoclinic-prismatic mineral containing arsenic, sulfur, and thallium.
The Century Dictionary and Cyclopedia
n. A rare sulpharsenide of thallium, TlAsS2, which occurs in complex monoclinic crystals of a cochineal-red color: found with realgar at Allchar, Macedonia.
Word Usage
"It forms a small number of rare minerals, including crookesite and lorandite."