Calcite, Rensselaer Quarry, Rensselaer, Indiana
This is a unique fluorescent calcite specimen from the Rensselaer Quarry, Pleasant Ridge, Jasper County, Indiana, that shows an unusual crystal habit consisting of a single mass of intergrown, doubly-terminated, highly-modified scalenohedrons. Under mid wave UV (302 nm), the calcite shows a lovely pastel pink fluorescent response. As is typical for the Rensselaer location, this specimen also has surface and included bitumen, which is also fluorescent. This specimen measures 107 x 65 x 46 mm and it weighs 294 grams.
The Rensselaer Quarry, also known as the Pleasant Ridge Quarry, is located approximately 3 miles east of Rensselaer, Indiana. The quarry is a former open pit producer of dolostone aggregate, but is now closed and flooded with water. Natural bitumen commonly permeates the dolostone and often coats the mineral specimens collected there.
As shown in the photograph above, this specimen is at its best under mid wave UV (302 nm). The calcite shows a pastel pink response, while the bitumen coating and inclusions fluoresce yellow-tan. The calcite is poorly fluorescent under short and long wave UV.
Same specimen shown under visible light. Note the translucent brown coloration of the calcite, due to bitumen stains and inclusions.