Siderite coating Calcite (rare locality specimen)

Item Description

One of only a handful of these pieces I have seen from this locality that lies east of the famous Mineral Farm on the road up to the Camp Bird Mine. The piece features a pair of intergrown scalenohedral Calcite crystals which are covered by hundreds of small, golden-brown scalenohedral Siderite crystals. A few smaller additional Calcites with the same Siderite coating can be seen on the piece. This is not a pseudomorph or even a "cast", but simply a coating of Siderite on Calcite. On the underside of the specimen, you can see an exposed area that shows the white Calcite inside of the fairly thick layer of overgrown Siderite. Great condition all the way around, as the crystals are undamaged on the display side, though the piece is contacted on the back. This was a very limited find, and a unique crystallization from the San Juan Mountains. The largest crystal measures 7.7 cm long. Valued at $600.