Lollingite 3.21 ct
Trillion Cut  7.90 x 7.90 x 4.68 mm

Lollingite or löllingite

is Iron arsenide with formula FeAs2 ,but it may contain nickel, cobalt and sulfur; the hardness is 5-5.5

Often mixed with very similar arsenopyrite ( FeAsS) ,therefore difficult to distinguish ,is only little bit softer.

It comes from

Coleman Township,Cobalt area, Cobalt- Gowganda region, Timiska mining District,Ontario,Canada