A very rich marcasite specimen covered by a layer of small but very sharp and brilliant crystals, with metallic reflections between gold and greenish tones, with iridescence.

These marcasite crystals show tabular forms and the Sperkise twin (from the German Speerkies –Speer: spear and Kies: rock-. It has been used as a synonym for marcasite specimens). This twin is characterized by being formed by 4 or 5 crystals cyclically disposed around a central axis parallel to c.