Transylvania

The mineral exists because of tens of thousands of cubic meters of fossil bat droppings.

J. Schadler described ardealite in 1932 from the dry Cioclovina Cave in the Sureanu Mountains, using Ardeal, the Romanian name for Transylvania. The cave held a large fossil guano phosphate deposit, much of it mined for fertilizer in the first half of the twentieth century. The same cave is now counted among the richest mineralogical caves in the world.