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Vivianite () is a hydrated iron phosphate mineral found in a number of geological environments. Small amounts of manganese Mn2+, magnesium Mg and calcium Ca may substitute for iron Fe2+ in the structure.〔Gaines et al (1997) Dana’s New Mineralogy Eighth Edition. Wiley〕 Pure fresh vivianite is colorless, but the mineral oxidizes very easily, changing the color, and it is usually found as deep blue to deep bluish green prismatic to flattened crystals. Vivianite crystals are often found inside fossil shells, such as those of bivalves and gastropods, or attached to fossil bone. It was named by Abraham Gottlob Werner in 1817, the year of his death, after John Henry Vivian (1785–1855), a Welsh-Cornish politician, mine owner and mineralogist living in Truro, Cornwall, England. John Vivian discovered the mineral at Wheal Kind, in St Agnes, Cornwall.〔 == Vivianite group == Vivianite group minerals have the general formula A3(X04)2·8H20, where A is a divalent transition metal cation and X is either phosphorus or arsenic, and they are monoclinic.〔Journal of the Russell Society (2006) 9:3〕 Group members are: :Related: : *Bobierrite Mg3(PO4)2·8H2O : *Symplesite Fe2+3(AsO4)2·8H2O : *Metaköttigite Zn3(AsO4)2·8H2O : *Metavivianite (Fe2+3-x,Fe3+x)(PO4)2(OH)x·8-xH2O.〔 :: *Note: Metavivianite, that vivianite readily alters to, is not a member of the vivianite group because it contains trivalent Fe3+ cations. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Vivianite」の詳細全文を読む スポンサード リンク
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