Oxy-dravite
San Martino al Cimino, Viterbo, Viterbo Province, Lazio, Italy
Grey prismatic crystals.
Ref.: Chukanov, N.V., Chervonnyi, A.D. (2016): Infrared spectroscopy of minerals and related compounds. Springer, Cham Heidelberg Dordrecht New York London, page 511.
Collection and photo: Giorgio Bortolozzi (specimen by H. Braith).