This piece is from Fresnillo in the Mun. de Fresnillo, Zacatecas, Mexico. This locale contains 50 different mineral species including pyrargyrite. It is a silver sulfide that conatains the elements Ag, Sb, and S. This specimen consists of an oval cluster of silver-black, crystals that have a sub-metallic luster. The crystals have intricate growth patterns with skeletal and hoppered growth. Photo 6 is of the reverse side. This is a thumbnail sized piece that measures 16 x 11 x 8 mm.