Fluorite and Willemite from the Red Cloud Mine, La Paz County, Arizona

Located in the Trigo Mountains of La Paz County, Arizona, the Red Cloud mine is a location famous for producing some of the best wulfenite specimens in the world. Not generally known, however, the Red Cloud mine is also a prolific source of beautiful fluorescent minerals. This example from the Red Cloud mine features a very pleasing color combination of intense blue fluorescent fluorite, pale blue/green willemite and minor red calcite. As seen in the following photographs, the willemite only responds under short wave UV (254nm) and the fluorite shows its brightest response under long wave (365nm). The size of this specimen is 73 x 58 x 43 mm, and it weighs 113 grams.

As seen in the above photograph, this Red Cloud mine specimen displays best under full wave UV (SW+MW+LW). The fluorite shows an intense blue/purple response, the willemite pale blue/green and the minor calcite fluoresces red.

The same specimen seen under short wave UV. The willemite fluoresces brightly and the fluorite is somewhat diminished compared to the full wave image at top.

After the short wave lamp is turned off, the willemite continues to phosphoresce. The fluorite also shows very brief, dim phosphorescence.

Under long wave UV the fluorite shows a bright and intense blue/purple fluorescent response, and the other minerals are not reactive. Due to limitations of the camera's image sensor, it was not possible to capture the true brightness of the long wave response as the eye sees it. When viewed in-person, the long wave response of this specimen appears much brighter.

Same rock seen under visible light.

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