In limestone caves, as an early stage of the breakdown of bat guano, in reaction with calcite.
IMA Status:
Valid Species (Pre-IMA) 1932
Locality:
From the Cioclovina Cave, Transylvania, Romania. In Italy, in the La Guangola Cave, near Altamura, Apulia. At the Magurata and Bacho Kuo Caves, Bulgaria. Link to MinDat.org Location Data.
Name Origin:
From "Ardeal," the old Romanian name for Transylvania.
Chemical Formula: 