, also known as löllingite
is an iron arsenide
mineral with formula FeAs2
. It is often found associated with arsenopyrite
(FeAsS) from which it is hard to distinguish. Cobalt
substitute in the structure. The orthorhombic
lollingite group includes the nickel
iron arsenide rammelsbergite
and the cobalt iron arsenide safflorite
It forms opaque silvery white orthorhombic prismatic crystals often exhibiting crystal twinning. It also occurs in anhedral masses and tarnishes on exposure to air. It has a Mohs hardness of 5.5 to 6 and a quite high specific gravity of 7.1 to 7.5. It becomes magnetic after heating.
Lollingite was first described in 1845 at the Lölling district in Carinthia, Austria. It is known by a number of synonyms including leucopyrite.