Dims: 4.0" x 3.5" x 2.3" (10.2 x 8.9 x 5.8 cm)
Wt: 1 lb., 2.2 oz. (517 g)
Denton Mine, Cave-In-Rock, Illinois, U.S.A.
This is one of the most unusual specimens I have seen come from the Cave-In-Rock locality. It consists of a cluster of cubic Fluorite that partially grows over a large, crystalline formation of sphalerite. The Fluorites have a pale violet coloration and a rather dull, waxy luster, and are transparent and clear, though the dull luster provides some interference. The largest of these crystals have dimensions that slightly exceed 1" (2.5 cm). The sphalerites seem to consist of countless tiny crystals that do not exceed 2 mm in any dimension. However, they are all aligned with each other so as to appear to form two large, intergrown crystals. Both the Fluorite and sphalerite are pervaded with many tiny but well-formed chalcopyrite crystals. These are visible both on the sphaerite's surface and trapped just under the surfaces of the Fluorites. They are not visible beneathe all of the faces, though. There is a small amount of a pale brown, sandy host rock on the specimen's underside.