Many of the geodes collected from the famous Dugway Geode Beds in the Utah West Desert show impressive green fluorescence under UV. This example shows a classic Dugway geode consisting of a rhyolitic shell containing a hollow interior lined with chalcedony, quartz druse, and aragonite. Under short wave UV the chalcedony shows green uranyl-activated fluorescence, and the aragonite shows a blue white response with bright and lasting off-white phosphorescence. There is also another minor, unknown mineral present that shows small spots of sky blue phosphorescence. These geodes are typically only weakly fluorescent, or not fluorescent, under long wave UV. This geode was collected in April of 2010, and measures 9.5 x 8.5 x 5.3 cm, and weighs 288 grams.
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