Mineral Specimen #4261 Two Generations Maganoan Calcite
Geevor Mine (North Levant Mine), Pendeen, St Just, St Just District, Cornwall, England,
5.8 x 5.1 x 5.5 cm
Ex. H. R. McBroom from a trade with Sam Weller, 1987
Despite the label listing this specimen as being Cobaltoan Calcite and Rhodochrosite, this appears to be Manganoan Calcite. This can be deduced by the fluorescence under UV. Also, Manganoan not Cobaltoan Calcite is listed for the location. There are two generations of Manganoan Calcite present. The first generation at the core of the specimen can only be observed on the bottom of the specimen. It is a rich pink color and translucent when back lit. Under UV, it strongly fluoresces. The outer, secondary Calcite is pink tinted, but much lighter in color. This outer layer is composed of a multitude of sharply point crystals and is epitaxially orientated. It also fluoresces them same color as the inner color but not as vividly.
The specimen is in good condition but there is an area at the top of the specimen where many of the terminations of the crystals are cleaved at the tips.
This mineral is also found in the following galleries: Minerals From Europe | Calcite | Fluorescents | Minerals Priced Between 50 and 99 Dollars