A very large showy specimen of lustrous, metallic berthierite crystals, with huge bladed clusters to over 10 cm. This is a remarkable, large, and frankly quite attractive cluster for the species, which is a rare Iron Antimony Sulfide. I have seen many smaller ones over the years, but only a few of this stature. This is from an old European collection, and is a significant specimen for this rare sulfide species (and the largest I have seen for sale) .