Emplaced on limestone matrix and totally covering the surface are sharp, intergrown splendent, silver gray crysyals of arsenopyrite, to 2 cm across. A few, colorless, lustrous and translucent quartz crystals, to 3 cm in length poke through the mass of arsenopyrite crystals. Beautiful large plate. Although not in the Heck collection of Mexican minerals as are most others in this update, this piece is from the Stoudt collection which I also recently acquired, and so fit well with the larger update