The best-known examples of Sal ammoniac, with their typical skeletal or dendritic
growths, are from Ravat, in the Tien Shan Mountains, Tajikistan.
Sal ammoniac was first described at Monte Somma, at Mount Vesuvius, Campania, Italy, where it formed from fumarole
activity on this famous volcano. Another important Italian volcanic
locality is the La Fossa Crater, on Vulcano Island, Italy. Other significant European localities include the São Pedro da Cova Mine, Gondomar, Portugal; and the Kladno Mine, Libušin, Bohemia, Czech Republic. In Mexico, Sal ammoniac has been found at the Paricutin volcano, Michoacan, Mexico. An interesting occurrence was the Huron River shale fire, Huron Co., Ohio, which formed complex microcrystals of Sal ammoniac.