Vivianite
Current inventory:  0 gems
 

  
Vivianite was named in 1817 after John Henry Vivian (1785-1855), a Welsh-Cornish mineralogist, of Truro, Cornwall, England, who discovered the mineral.

Discovered in 1817; IMA status: Valid (pre-IMA; Grandfathered)

Chemistry

Chemical Formula:

Fe²⁺₃(PO₄)₂ • 8H₂O

Hydrated Iron Phosphate

Molecular Weight:

501.61 gm

Composition:

Iron

33.40 %

Fe

42.97 %

FeO

Phosphorus

12.35 %

P

28.30 %

P₂O₅

Hydrogen

3.22 %

H

28.73 %

H₂O

Oxygen

51.03 %

O

100.00 %

100.00 %

= TOTAL OXIDE

Classification

Mineral Classification:

Phosphates

Strunz 8th Ed. ID:

7/C.13-40

Nickel-Strunz 10th Ed. ID:

8.CE.40

8 : PHOSPHATES, ARSENATES, VANADATES
C : Phosphates without additional anions, with H₂O
E : With only medium-sized cations, RO₄:H₂O about 1:2.5

Related to:

Vivianite Group

Members of Group:

Vivianite Group: Annabergite, Arupite, Baricite, Erythrite, Hörnesite, Köttigite, Manganohörnesite, Parasymplesite, Vivianite

Varieties:

None

Synonyms:

Angelardite, Anglarite (of Berthier), Anglarite (of Kobell), Blue Iron Earth, Blue Ocher, Glaucosiderite, Mullicite, Native Prussian Blue, Paravivianite, Phosphate of Iron

Crystal Data

Crystallography:

Monoclinic - Prismatic

Crystal Habit:

Prismatic crystals, to 1.3 m; flattened on [100] or [010], somewhat elongated along [100], many modifying forms, dominated by {100}, [010}, may be rounded or corroded; stellate groups, incrustations, concretionary, earthy, powdery.

Twinning:

Translation gliding T(010), t[001]

Physical Properties

Cleavage:

Perfect on {010}

Fracture:

Fibrous

Tenacity:

Flexible, Sectile

Moh's Hardness:

1.5 - 2.0

Density:

2.60 - 2.70 (g/cm³)

Luminescence:

Not Fluorescent

Radioactivity:

Not Radioactive

Other:

Readily soluble in acids. Melting point = 1114°. Darkens in colour in H2O2.

Optical Properties

Color:

Colorless, very pale green, with oxidation becoming dark blue, dark greenish blue, Indigo-blue, then black; colorless to blue in transmitted light

Transparency:

Translucent, Transparent

Luster:

Vitreous. Pearly on cleavages. Dull when earthy

Refractive Index:

1.579 - 1.675  Biaxial ( + )

Birefringence:

0.0470 - 0.0730

Dispersion:

Weak; r < v

Pleochroism:

Visible.
X = blue, deep blue, Indigo-blue;
Y = pale yellowish green, pale bluish green, yellow-green;
Z = pale yellowish green, olive-yellow

Other:

The refractive indices increase with increasing oxidation, the birefringence decreases, and the pleochroism on {010} becomes stronger. 

Occurances

Geological Setting:

A secondary mineral in the oxidized zone of metallic ore deposits and complex granite pegmatites; replacing organic material in fossil bones, lake sediments, and in bog-iron ores and peat bogs; rarely in caves.

Common Associations:

Limonite, Ludlamite, Metavivianite, Pyrite, Pyrrhotite, Santaclarite

Common Impurities:

Mn, Mg, Ca

Type Locality:

Wheal Kind (Wheal Kine), West Wheal Kitty group, St Agnes, St Agnes District, Cornwall, England, UK

Year Discovered:

1817

View mineral photos:

Vivianite Mineral Photos and Locations

More Information

Mindat.org
Webmineral.com

Vivianite is an extremely rare gem mostly due to its difficulty of faceting. It is very soft, fibrous and somewhat flexible. It is a very attractive mineral specimen with vibrant colors. Vivianite is sometimes found inside fossil clam or snail shells or attached to fossil animal bone. Vivianite should be kept from long exposure to light as this can cause it to darken to nearly black. When found fresh the mineral may be colorless, or nearly colorless, and once exposed, will oxidize darkening to dark blue or blue-green. The darkening is from oxidation of the iron.

Vivianite is found in numerous localities, even for well-crystallized material. In England, from [Wheal Kind,] St. Agnes, and other mines in St. Just and Kea, Cornwall. At Hagendorf, Bavaria, Germany. From the Stari Trg mine, Trepca, Serbia. On the Taman Peninsula, Russia. Around Kerch, Crimean Peninsula, Ukraine. Huge crystals from Anloua, near Ngaoundéré, Cameroon. In the USA, from the Blackbird Mine, Lemhi County, Idaho; in the Treece and Ibex mines, Leadville, Lake County, Colorado; at the Bingham Canyon mine, Salt Lake County, Utah; from Richmond, Henrico County, Virginia; at the Foote mine, Kings Mountain, Cleveland County, North Carolina. In Mexico, from Santa Eulalia, Chihuahua. In Brazil, from the Énio pegmatite mine, northeast of Galiléia, Minas Gerais. Exceptional examples from Bolivia, at Poopo, Llallagua, Avicaya, Tazna, Monserrat, Morococala, Tatasi, and elsewhere. In the Ashio mine, Tochigi Prefecture, Japan.
 

  
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