Variscite is a rare mineral formed by phosphate rich water deposits that react with aluminum rich rocks in a near-surface environment. It is rarely found in crystals that are large enough to see without magnification, instead it usually occurs in veins, or cavity fillings.
Variscite was originally discovered in Germany in 1837 and its name is derived from Variscia, the historical name of the town where it was first found. It is also found in Australia, Brazil, Poland, Spain and the United States.
The most sought after Variscite specimens in the world come from the Little Green Monster Mine, in Utah, the photo below was taken there in 1937 and is titled "Ed and Variscite nodules" (source - mindat.org).