Vivianite

vivianite

metavivianite

parasymplesite

ludlamite

Images

Formula: Fe2+3(PO4)2.8H2O
Hydrated phosphate, vivianite group
Specific gravity: 2.6 to 2.7
Hardness: 2
Streak: White to faintly light blue
Colour: Green to blue
Solubility: Readily soluble in hydrochloric acid and sulphuric acid; slightly soluble in nitric acid
Common impurities: Mn,Mg,Ca
Environments:

Pegmatites
Sedimentary environments
Hydrothermal environments

Vivianite is a secondary mineral which is a weathering product of primary iron and manganese phosphates in granite pegmatites, in the oxidation zone of metal ore deposits, particularly associated with gossan, in the oxidation zone of hypothermal (high temperature) hydrothermal veins, in clay sediments, and in recent alluvial deposits replacing organic material, peat, lignite, bog iron ores and forest soils (Mindat, Dana, Webmin, HOM). Associated minerals include metavivianite, limonite, ludlamite, pyrite, pyrrhotite, santaclaraite and siderite (HOM, Mindat).

Localities

At Llallagua, Bolivia, vivianite crystals to 10 cm occur on a goethite matrix derived from the alteration of pyrite and marcasite. Associated minerals include childrenite, cronstedtite, pyrrhotite, franckeite and sphalerite (Minrec 37.2.156).

At the Cigana mine, Minas Gerais, Brazil, good vivianite crystals occur on a matrix of muscovite, some with druses of pyrite (Minrec 35.3.252).

At Trepča, Kosovska Mitrovica, District of Mitrovica, Kosovo, vivianite crystals to 10 cm occur, resting on pyrrhotite or pyrite, and in some cases on quartz or carbonate (MinRec 38.4.290).

The type locality is Wheal Kine, St Agnes Consols, St Agnes, Cornwall, England, UK.

At Burdell Gill, Caldbeck Fells, Cumbria, England, UK, vivianite-parasymplesite occurs as tiny sheaves of blades to about 0.2 mm on gossanous quartz. It is often associated with corroded bariopharmacosiderite from which it appears to have formed. The vivianite and parasymplesite appear to have been confined to the isolated blocks that also carried the switzerite and rhodochrosite (JRS 8(1).1-9).

At the Blackbird mine, Lemhi county, Idaho, USA, some of the finest specimens of vivianite have been found. They occur to 22 cm on altered schist and on white quartz. Associated minerals include ludlamite, quartz and siderite (Minrec 41.4.366-369).

At the Bayport limestone quarries, Bellevue, Eaton County, Michigan, USA, vivianite has been found in a pyrite-rich shale breccia in limestone (R&M 93.3.230).

At the Chickering Mine, Walpole, Cheshire County, New Hampshire, USA, vivianite occurs rarely in the pegmatite. When found, it is as crystals or fibrous masses in zones of hydrothermally altered triphylite. Associated minerals include siderite, quartz, fluorapatite, ludlamite and, rarely, whitmoreite (R&M 90.5.421).

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