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Danburite from Charcas, San Luis Potosi, Mexico

Danburite is a calcium borosilicate mineral that is sometimes cut as a gemstone. Like many minerals, when found in its pure form it is not fluorescent, but when trace amounts of certain impurities are present it glows in beautiful colors under UV light. This is an example of a brightly fluorescent danburite specimen from Charcas, San Luis Potosi, Mexico. It consists of a radiating cluster of translucent white danburite crystals to 2.8 cm in length, and overall measures 66 x 56 x 44 mm in size. Under short and mid wave UV a green fluorescent response is seen, no doubt due to the presence of trace amounts of the uranyl ion (uranium). Under long wave UV the fluorescence is more of a cream/white color, with hints of green. The fluorescent activator responsible for the cream/white response is not known.

As seen in the above photograph, this danburite specimen shows its brightest fluorescent response under mid wave UV (304nm). The green luminescence is due to the presence of trace amounts of the element uranium, in the form of the uranyl ion.

A similar, but somewhat less bright response is seen under short wave UV (254nm).

A different fluorescent response is seen under long wave UV (365nm), showing a more cream/white color with just a hint of green.

The same specimen seen under visible light.

Photo montage showing a comparison of the fluorescent response of the danburite cluster under each UV wavelength and visible light.

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