Wiktionary
corderoite
n. (context mineral English) An isometric-tetartoidal mineral containing chlorine, mercury, and sulfur.
Wikipedia
Corderoite
Corderoite is an extremely rare mercury sulfide chloride mineral with formula HgSCl. It crystallizes in the isometric crystal system. It is soft, 1.5 to 2 on the Mohs scale, and varies in color from light gray to black and rarely pink or yellow.
It was first described in 1974 for occurrences in the McDermitt Mercury mine in Humboldt County, Nevada. The name is from the old name of the mine, the Old Cordero Mine.