Calcite, Valders Quarry, Manitowoc, Wisconsin

Plate of scalenohedral calcite crystals showing an unusual purple/blue fluorescent response under mid wave UV (302 nm). This specimen is from an uncommon midwestern location; the Valders Quarry, in Valders, Manitowoc County, Wisconsin. The size of this piece is 89 x 54 x 51 mm, and it weighs 237 grams.

The Valders Quarry is an open pit dolomitic limestone quarry, which produces harbor rock, gravel, and a very hard and weather resistant type of marble. It is located in the town of Valders, east of Manitowoc, in east central Wisconsin.

As shown in the above photograph, an unusual purple/blue fluorescent response is seen under mid wave UV. Interestingly, the calcite is not significantly fluorescent under short or long wave UV.

The same specimen shown under visible light. This piece consists of a plate of milky white, translucent, scalenohedral calcite crystals and minor marcasite on a flat matrix of light grey limestone/dolostone.

Composite photograph showing fluorescent response under mid wave UV and the specimen under visible light.

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