Calcite (Manganese-bearing) with orange Baryte

Item Description

The Montreal Mine in Wisconsin is a famous iron mine, producing iconic specimens of Hematite, Rhodochrosite Baryte and Manganese-bearing Calcite. This piece is an unusual example, not for the Calcite but rather the associated Baryte crystals which have a distinct ORANGE hue, resembling bladed Wulfenite more than Baryte. My guess is that either iron or manganese is contributing to the color, but you don't see many Barytes with that hue from any locality. The main focus of the specimen are the Calcites, which have formed somewhat spherical aggregates comprising tightly intergrown rhombs, with a lovely vitreous luster . The largest Calcite "ball" measures about 1.0 cm cross, most of them have a gentle pink hue from manganese content. Another great aspect of the piece is that the Calcite groups are slightly translucent, passing light when backlit, which is not always the case with the material, as many of the pink Calcites from the Montreal Mine are essentially opaque. No major damage to the central Calcite aggregates, only peripheral roughness where the piece was removed from the pocket wall. The label accompanying the piece states it was likely collected in the 39th-40th levels of the mine (3900-4000 feet) and was mined circa 1940s-1950s.
From the collection of longtime mineral collector Dr. Bob Lauf (Collection #2750), the author of the Mineral Collectors Guide books (Schiffer Publishing), widely seen at mineral shows and libraries. Robert Lauf grew up in Chicago and attended the University of Illinois, ultimately receiving a Ph.D. in Metallurgical Engineering. His scientific career included over twenty years at Oak Ridge National Laboratory, where he conducted research on topics ranging from nuclear fuel, coal by-products, materials synthesis, microwave processing, sensors, optical materials, and biomineralization. He has been granted over forty U.S. Patents for his inventions, many of which have become successful industrial products. He is now a Registered Patent Agent and technology consultant.