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Formula:   Fe3(PO4)2 •8H2O   mineral photo

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Crystal:   Monoclinic  
Hardness:   1.5-2  
Spec. Gr.:   2.68  
Streak:   White  
Cleavage:   Perfect cleavage in one direction  
Location:   Llallagua,

Vivianite is a hydrous ferrous phosphate. An uncommon mineral, but one that forms near the earth's surface when waters charged with phosphoric acid act on primary ores of pyrite and other minerals rich in iron. It forms in beautiful, well-crystallized tabular green crystals at St. Agnews, Cornwall, England; Llallagua, Bolivia; and in enormous crystals, up to a meter in length, at Anloua, Cameroon. Interesting crystals have formed within fossil shells (particularly clams), and bones in peat iron ore in Kerez, Crimea, USSR.

Bibliography: Svenek, Jaroslav, Minerals, 1987, pg. 162-163.

University of California, Santa Barbara—Department of Earth Science
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