Alum Cave, Vulcano Island, Sicily, Italy
Speleothems: very small crystals
Frequency: Rare
Other occurrence: small flowers or elongated fibers
Location within cave: all over the cave (initially the mineral was so abundant, that the cave functioned as an alum mine for tens of years)
First description of cave occurrence: Cossa, A. 1878. Ricerche Chimiche. Academia Lincei Roma 3(2): 7
First description of non-cave occurrence: Palache, C., Berman, H. & Frondel, C. 1951. 29.5.5.2 Soda alum [NaAl(SO4)2·12H2O], in The System of Mineralogy, Volume II, Seventh Edition John Wiley and Sons, Inc New York: 474
volcanic tuff
Group: Sulfates
Chemical formula: NaAl(SO4)2·12H2O
[According to the official IMA-CNMNC List of Mineral Names (http://nrmima.nrm.se/imalist.htm)]
Deposition and stability: Its formation is related to the fumarole activity and to the acid weathering of volcanic ash and tuff
It occurs mixed with Alum-(K), sometimes growing over hallotrichite fibers
- Isometric