Siderite ("rosettes") on Sphalerite (ex Richard A. Kosnar Collection)

Item Description

These classic Siderite specimens from the Eagle Mine are some of the most recognizable and attractive carbonates from Colorado. They are not the typical blocky rhombic habit like those seen from a lot of other ore bodies in Colorado, but rather highly compressed rhombs that can often form beautiful "rosettes". This very large, aesthetic, "museum" piece hosts hundreds of sharp, golden color flattened rhombohedra of Siderite on a layer of black Sphalerite on matrix. The largest crystals measures 1.2 cm across. This tremendous zinc mine near the former town of Gilman (now a ghost town) is long defunct and will never produce these specimens again. They are highly prized among Colorado collectors for their unique form and obvious beauty. I can't find any damage of note, and the piece sits and displays beautifully as you can see from the photos. The piece was from the collection of Richard A. Kosnar (Catalogue No. Sid/Sph1C). Valued at $3,500 and possibly more based upon the relative obscurity on the matrix these days.