Cave-In-Rock, Hardin County, Illinois

The Fluorite on this specimen is colored a nice blue color on a lower layer of pale yellow/brown. There are numerous double terminated Calcite crystals with a coating on an unidentified white material. Of note are the irregular voids in the bottom of the specimen. There is a bit of speculation regarding the formation of these voids. On numerous occasions, I have seen specimens labeled indicating this was due to dripping acid. This seems unlikely since Fluorite is fairly resistant to acid and any acid which could cause such a void would probably etch the surface of the crystals. More likely, this is a cast after Barite which was dissolved by a hydrofluoric solution to which Fluorite is impervious. The specimen is in fairly good condition. The largest crystal has no damage other than internal cleavages. The crystals at the front of the specimen in the photos are damaged. The other crystal (at the right in the photos) has some small damage to its corner.

From the Don Langham collection

6.5 x 6.3 x 5.2 cm

$25      Click here to order this mineral.