Youngite, from the Youngite Caves, Guernsey, Wyoming

Fluorescent youngite specimen from Guernsey, Wyoming. Youngite is an agatized brecciated jasper with a coating of grayish translucent druzy quartz. Found in only one location, the youngite caves near Guernsey, Platte Co., Wyoming. The fluorescent response of youngite under UV is highly variable, with some specimens showing spectacular fluorescence, and others being only dimly fluorescent. This specimen is about the best I’ve seen. Under SW UV the drusy quartz fluoresces green, and the jasper center fluoresces a blue/grey color with deep blue phosphorescence. Under mid wave UV This piece looks like an entirely different specimen, with the quartz druse showing a beautiful pastel blue and green fluorescence, and the jasper fluorescing a cream/brown color. The jasper is also dimly phosphorescent after mid wave UV. The long wave response is more subtle, with the jasper responding a brighter cream/brown and the quartz druse fluorescing darker green. The size of this specimen is 10.2 x 8.9 x 5.1 cm, and it weighs 269 grams.

The Youngite caves are located on private property, and have been off-limits to collectors for years.

Click on the gallery images above for a larger view.

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