Dims: 1.5" x 0.6" x 0.5" (3.8 x 1.5 x 1.3 cm)
Wt: 10.3 g
Santo Nino vein, Fresnillo, Zacatecas, Mexico
This large thumbnail specimen consists of several warped, intergrown Pyrargyrite crystals. They have forms that are rather difficult to determine due to damage and their intergrowth, and their moderate gray coloration and metallic luster look like those of a variety of related minerals. However, they have one trait that discerns them from all others. When one holds the specimen up to the light, the Pyrargyrite will glow with a deep red translucence. However, there is some material on the specimen that does not glow this color. It shows much better, more defined crystal form than the Pyrargyrite, and its gray color is a bit darker. Also, its luster is not quite as bright, and its crystals show lengthwise striations that I do not see on the Pyrargyrite specimens that I have available for examination. I believe that this material is a closely-related sulfide, possibly Argentite or Stephanite. Interestingly, it surrounds a Pyrargyrite crystal, the termination of which is the only visible portion. I have affixed it inside a domed plastic thimble box for display.