Dims: 2.9" x 2.1" x 1.5"(7.4 x 5.3 x 3.8 cm)
Wt: 6.27 oz.177.8 g)
Noche Buena, Durango, Mexico
This specimen contains hundreds of fibrous, needle-like Boulangerite crystals on a matrix of sphalerite and calcite. The Boulangerites reach a maximum length of about 0.5"(1.3 cm) and are thinner than human hairs. They have a gray color and metallic luster, and are congregated into a dense matting that covers at least 30% of the host rock's surface area. Given the crystals' occurrence as superfine needles, this specimen should be handled as little as possible and with great care, as many of the needles are loose and will easily come off onto one's hands and clothes, and whatever else may be underneath it. The calcites in the host rock are small and mostly broken, but a few thin dogtooth crystals are intact. There is a lot of sphalerite, though, and it occurs in large, well-formed prismatic crystals with a deep brown color and subadamantine luster. I really like these thin needles- there aren't many metallic minerals that occur in such a form for this price.