Thallium(I) sulfide

Thallium(I) sulfide, also known as thallous sulfide, is a chemical compound. Its chemical formula is Tl2S. It has thallium and sulfide ions in it. The thallium is in its +1 oxidation state.
Properties.
Thallium(I) sulfide is a black solid. It reacts with acids to make hydrogen sulfide and a thallium salt. 
Occurrence and preparation.
It is found as a mineral called carlinite, but it is rare. It is the only thallium sulfide mineral that does not have another metal in it. It is made in the laboratory by reacting thallium(I) sulfate with hydrogen sulfide or by heating thallium and sulfur together.
Uses.
It was used in some of the first infrared detectors. One of the first reliable infrared detectors used thallium sulfide and it was made in World War II.