Wikipedia
Coccinite
Coccinite is a rare mercury iodide mineral with chemical formula of HgI, mercury(II) iodide. in addition to its discovery locality of Casas Viejas, Mexico, it has also been reported from Broken Hill, New South Wales, and from a uranium mine in Thuringia and old mercury workings in the Rhineland-Palatinate in Germany. At the Thuringia deposit the mineral occurs as a sublimation product resulting from fires associated with pyrite bearing, graptolitic slate.