Dims: 0.7" x 0.6" x 0.3" (1.8 x 1.5 x 0.8 cm)
Wt: 1.5 g
Sirena Mine, Guanajuato, Mexico
This small thumbnail specimen consists of a cluster of cubic Acanthite crystals. I don't exactly understand the concept, but apparently these crystals are pseudomorphs after argentite, a mineral with the same chemical composition as Acanthite, but with a different structure. Needless to say, they have a definitely cubic form. The cluster is rather flat and shaped like an inverted triangle; it has a branching habit that appears nearly arborescent in some ways, but mostly resembles the form of laboratory-grown bismuth crystals. Together, the crystals form a stepped "hopper effect". None of the individual crystals exceed 3 mm in any dimension, and all have a metallic luster and a dark gray color with subtle tinges of colorful iridescence. I have affixed the specimen in a domed plastic thimble box for display and protection purposes. It is a superb little piece with no detectable damage.