Dims: 3.1" x 1.6" x 1.4"(7.9 x 4.1 x 3.6 cm)
Wt: 2.86 oz.(81.2 g)
Grey Horse Mine, Pinal County, Arizona, U.S.A.
Though it seems to show some heavy damage, this Vanadinite specimen has some very unusual traits that make it worth a look. The crystals are a moderate golden-orange color and translucent. Their luster decreases as the crystals gain size, so that the smallest crystals(less than 2 mm in length) have an adamantine luster, and the largest crystals(3-5 mm in length) have a pearly luster. They occur in a hexagonal prismatic form, but the larger crystals are odd in that they often are hollow, due to their edges and prism faces growing much more quickly than their cores, so that a hopper crystal effect is evident. Many of these hopper crystals are so warped as to be incomplete, but there are several complete ones wherein the effect can be easily seen. Most of the Vanadinite crystals rest on a bed of massive quartz that coats the host rock, which appears to be made of shale. Crevices in the underside of the host rock are filled with loose, individual parallel fibers that run perpendicular to the crevices' lengths. I have no idea what they are composed of, and I have never before seen anything like them in a specimen from this locality.