What is "aktashite"

n. (context mineral English) A trigonal-pyramidal grayish black mineral containing arsenic, copper, mercury, and sulfur.

Aktashite is a rare arsenic sulfosalt mineral with formula CuHgAsS. It is a copper mercury-bearing sulfosalt and is the only sulfosalt mineral with essential Cu and Hg yet known. It is of hydrothermal origin. It was published without approval of the IMA/CNMNC.