Dims: 2.58x2.50x1.43" (6.56x6.34x3.64cm)
Wt: 7.51oz (213g)
Morenci Mine, Greenlee County, Arizona, USA
This rock displays brochantite crystals on several sides. While flat, they are not properly a crust as they are simply flat crystals, generally with a radial form, against the side of the rock, and likely formed in a crevice. A loupe reveals that these brochantite crystals are a brilliant green, highly transparent, and with a vitreous luster. Most brochantite is acicular, so these are nice crystals. Some of them show rounded terminations that help to distinguish these from their close cousin antlerite. Under the brochantite is another mineral, opaque and black, with the same form. Either the brochantite is an oxidation product of this mineral, or they are both brochantite with the earlier growth having the black appearance.