Vivianite 2 w-triphylite and feldspar (Hydrous iron phosphate Custer County South Dakota 1652

Vivianite () is a hydrated

iron Iron () is a chemical element with symbol Fe (from la, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, right in ...

phosphate mineral Phosphate minerals contain the tetrahedrally coordinated phosphate (PO43−) anion along sometimes with arsenate (AsO43−) and vanadate (VO43−) substitutions, and chloride (Cl−), fluoride (F−), and hydroxide (OH−) anions that also fit ...

found in a number of geological environments. Small amounts of

manganese Manganese is a chemical element with the symbol Mn and atomic number 25. It is a hard, brittle, silvery metal, often found in minerals in combination with iron. Manganese is a transition metal with a multifaceted array of industrial alloy u ...

Mn²⁺,

magnesium Magnesium is a chemical element with the symbol Mg and atomic number 12. It is a shiny gray metal having a low density, low melting point and high chemical reactivity. Like the other alkaline earth metals (group 2 of the periodic ...

Mg and

calcium Calcium is a chemical element with the symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar t ...

Ca may substitute for

Fe²⁺ in the structure.Gaines et al (1997) Dana’s New Mineralogy Eighth Edition. Wiley Pure vivianite is colorless, but the

mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. Rafferty, ed. ...

oxidizes very easily, changing the color, and it is usually found as deep blue to deep bluish green

prismatic An optical prism is a transparent optical element with flat, polished surfaces that are designed to refract light. At least one surface must be angled — elements with two parallel surfaces are ''not'' prisms. The most familiar type of opti ...

to flattened crystals.
Vivianite crystals are often found inside

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

shells, such as those of

bivalve Bivalvia (), in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class of marine and freshwater molluscs that have laterally compressed bodies enclosed by a shell consisting of two hinged parts. As a group, biv ...

s and gastropods, or attached to fossil bone. It was named by

Abraham Gottlob Werner Abraham Gottlob Werner (; 25 September 174930 June 1817) was a German geologist who set out an early theory about the stratification of the Earth's crust and propounded a history of the Earth that came to be known as Neptunism. While most ten ...

in 1817, the year of his death, after either John Henry Vivian (1785–1855), a Welsh-Cornish politician, mine owner and mineralogist living in

Truro Truro (; kw, Truru) is a cathedral city and civil parish in Cornwall, England. It is Cornwall's county town, sole city and centre for administration, leisure and retail trading. Its population was 18,766 in the 2011 census. People of Truro c ...

, Cornwall, England, or after Jeffrey G. Vivian, an English mineralogist. Vivianite was discovered at Wheal Kind, in

St Agnes, Cornwall St Agnes ( kw, Breanek) is a civil parish and a large village on the north coast of Cornwall, UK. The village is about five miles (8 km) north of Redruth and ten miles (16 km) southwest of Newquay. ''and'' An electoral ward exists ...

Vivianite group

Vivianite group minerals have the general formula A₃(XO₄)₂·8H₂O, where A is a

divalent In chemistry, the valence (US spelling) or valency (British spelling) of an element is the measure of its combining capacity with other atoms when it forms chemical compounds or molecules. Description The combining capacity, or affinity of a ...

transition metal In chemistry, a transition metal (or transition element) is a chemical element in the d-block of the periodic table (groups 3 to 12), though the elements of group 12 (and less often group 3) are sometimes excluded. They are the elements that c ...

cation An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by conve ...

and X is either

phosphorus Phosphorus is a chemical element with the symbol P and atomic number 15. Elemental phosphorus exists in two major forms, white phosphorus and red phosphorus, but because it is highly reactive, phosphorus is never found as a free element on Ea ...

arsenic Arsenic is a chemical element with the symbol As and atomic number 33. Arsenic occurs in many minerals, usually in combination with sulfur and metals, but also as a pure elemental crystal. Arsenic is a metalloid. It has various allotropes, bu ...

, and they are

monoclinic In crystallography, the monoclinic crystal system is one of the seven crystal systems. A crystal system is described by three vectors. In the monoclinic system, the crystal is described by vectors of unequal lengths, as in the orthorhombic ...

.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 Metavivianite () is a hydrated iron phosphate mineral found in a number of geological environments. As a secondary mineral it is typically formed from oxidizing vivianite. Metavivianite is typically found as dark blue or dark green prismatic to f ...

(Fe²⁺,Fe³⁺)(PO₄)₂(OH)·H₂O. ::*Note: Metavivianite, that vivianite readily alters to, is not a member of the vivianite group because it contains

trivalent In chemistry, the valence (US spelling) or valency (British spelling) of an element is the measure of its combining capacity with other atoms when it forms chemical compounds or molecules. Description The combining capacity, or affinity of a ...

Fe³⁺ cations.

Structure

In pure end member vivianite all the iron is

, Fe²⁺, but there are two distinct sites in the structure that these

ions An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by conve ...

can occupy. In the first site the Fe²⁺ is surrounded by four

water Water (chemical formula ) is an inorganic, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as ...

molecules A molecule is a group of two or more atoms held together by attractive forces known as chemical bonds; depending on context, the term may or may not include ions which satisfy this criterion. In quantum physics, organic chemistry, and bioc ...

and two

oxygen Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as we ...

s, making an

octahedral In geometry, an octahedron (plural: octahedra, octahedrons) is a polyhedron with eight faces. The term is most commonly used to refer to the regular octahedron, a Platonic solid composed of eight equilateral triangles, four of which meet at ea ...

group. In the second site the Fe²⁺ is surrounded by two water molecules and four oxygens, again making an octahedral group. The oxygens are part of the

phosphate In chemistry, a phosphate is an anion, salt, functional group or ester derived from a phosphoric acid. It most commonly means orthophosphate, a derivative of orthophosphoric acid . The phosphate or orthophosphate ion is derived from phosph ...

groups (PO₄)⁻³, that are

tetrahedral In geometry, a tetrahedron (plural: tetrahedra or tetrahedrons), also known as a triangular pyramid, is a polyhedron composed of four triangular faces, six straight edges, and four vertex corners. The tetrahedron is the simplest of all the ...

. The vivianite structure has chains of these octahedra and tetrahedra that form sheets perpendicular to the a crystal axis. The sheets are held together by weak bonds, and that accounts for the perfect cleavage between them.
The crystals are

, class 2/m,

space group In mathematics, physics and chemistry, a space group is the symmetry group of an object in space, usually in three dimensions. The elements of a space group (its symmetry operations) are the rigid transformations of an object that leave it ...

C 2/m, with two formula units per

unit cell In geometry, biology, mineralogy and solid state physics, a unit cell is a repeating unit formed by the vectors spanning the points of a lattice. Despite its suggestive name, the unit cell (unlike a unit vector, for example) does not necessari ...

(Z = 2). The approximate values of the unit cell parameters are :a = 10.1 Å, b = 13.4 Å, c = 4.7 Å and β = 104.3°, with slightly different values given by different sources: :a = 10.086 Å, b = 13.441 Å, c = 4.703 Å, β = 104.27° :a = 10.06 Å, b = 13.41 Å, c = 4.696 Å, β = 104.3° :a = 10.034–10.086 Å, b= 13.434–13.441 Å, c= 4.687–4.714 Å, β = 102.65–104.27° :a = 10.024(6) Å, b = 13.436(3) Å, c = 4.693(4) Å, β = 102.30(5)°

Appearance

The mineral may occur as crystals, or as masses or

concretions A concretion is a hard, compact mass of matter formed by the precipitation of mineral cement within the spaces between particles, and is found in sedimentary rock or soil. Concretions are often ovoid or spherical in shape, although irregular ...

. The crystals are usually

parallel to the c crystal axis, and flattened perpendicular to the b axis.

Equant Equant (or punctum aequans) is a mathematical concept developed by Claudius Ptolemy in the 2nd century AD to account for the observed motion of the planets. The equant is used to explain the observed speed change in different stages of the plan ...

crystals are rarer. They may also occur as stellate (star-shaped) groups, or encrustations with a bladed or

fibrous Fiber or fibre (from la, fibra, links=no) is a natural or artificial substance that is significantly longer than it is wide. Fibers are often used in the manufacture of other materials. The strongest engineering materials often incorpora ...

structure. Unaltered specimens are colorless to very pale green, but they

oxidize Redox (reduction–oxidation, , ) is a type of chemical reaction in which the oxidation states of substrate (chemistry), substrate change. Oxidation is the loss of Electron, electrons or an increase in the oxidation state, while reduction ...

on exposure to light (and possibly also in situ) to blue, then darker green, brown, purple and purplish black. The streak is white, altering to dark blue or brown. Crystals are transparent to translucent with a vitreous luster, pearly on the cleavage surface, or dull and earthy.

Optical properties

Vivianite is biaxial (+) with refractive indices approximately :n_α = 1.58, n_β = 1.6, n_γ = 1.6, but different sources give somewhat different values :n_α = 1.579, n_β = 1.602, n_γ = 1.637 :n_α = 1.579–1.616 n_β = 1.602–1.656 n_γ = 1.629–1.675 :n_α=1.58–1.626, n_β=1.598–1.662, n_γ=1.627–1.699 Birefringence: δ = 0.050–0.059 or 0.0470–0.0730 The refractive indices increase with increasing oxidation, the birefringence decreases, and the pleochroism on becomes stronger.
The angle between the optic axes, 2V, has been measured as between 63° and 83.5°; it can also be calculated from the refractive indices, giving a value between 78° and 88°. The dispersion of the optic axes is weak, with r or non-existent.
Vivianite is pleochroic with X= blue, deep blue or indigo-blue; Y= pale yellowish green, pale bluish green or yellow-green; Z= pale yellowish green or olive-yellow. X is parallel to the b crystal axis and Z is inclined to the c crystal axis at an angle of 28.5°. It is not fluorescent.

Physical properties

Vivianite is a soft mineral, with

Mohs hardness The Mohs scale of mineral hardness () is a qualitative ordinal scale, from 1 to 10, characterizing scratch resistance of various minerals through the ability of harder material to scratch softer material. The scale was introduced in 1812 by the ...

only to 2, and

specific gravity Relative density, or specific gravity, is the ratio of the density (mass of a unit volume) of a substance to the density of a given reference material. Specific gravity for liquids is nearly always measured with respect to water (molecule), wa ...

2.7. It splits easily, with perfect cleavage perpendicular to the b crystal axis, due to the sheet-like structure of the mineral. It is sectile, with a fibrous fracture, and thin laminae parallel to the cleavage plane are flexible. It is easily soluble in acids.
It has a melting point of , it darkens in color in H₂O₂ and is not radioactive.

Geological setting

Vivianite is a secondary mineral found in a number of geologic environments: The

oxidation zone Redox (reduction–oxidation, , ) is a type of chemical reaction in which the oxidation states of substrate change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is the gain of electrons or a d ...

of metal ore deposits, in

granite Granite () is a coarse-grained ( phaneritic) intrusive igneous rock composed mostly of quartz, alkali feldspar, and plagioclase. It forms from magma with a high content of silica and alkali metal oxides that slowly cools and solidifies und ...

pegmatites containing

minerals, in

clays Clay is a type of fine-grained natural soil material containing clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4). Clays develop plasticity when wet, due to a molecular film of water surrounding the clay part ...

and glauconitic sediments, and in recent

alluvial Alluvium (from Latin ''alluvius'', from ''alluere'' 'to wash against') is loose clay, silt, sand, or gravel that has been deposited by running water in a stream bed, on a floodplain, in an alluvial fan or beach, or in similar settings. Al ...

deposits replacing organic material such as

peat Peat (), also known as turf (), is an accumulation of partially decayed vegetation or organic matter. It is unique to natural areas called peatlands, bogs, mires, moors, or muskegs. The peatland ecosystem covers and is the most efficien ...

, lignite,

bog iron Bog iron is a form of impure iron deposit that develops in bogs or swamps by the chemical or biochemical oxidation of iron carried in solution. In general, bog ores consist primarily of iron oxyhydroxides, commonly goethite (FeO(OH)). Iron-bear ...

ores and forest soils (All). Bones and teeth buried in peat bogs are sometimes replaced by vivianite. Some authors say that it is particularly associated with

gossan Gossan (eiserner hut or eisenhut) is intensely oxidized, weathered or decomposed rock, usually the upper and exposed part of an ore deposit or mineral vein. In the ''classic'' gossan or iron cap all that remains is iron oxides and quartz, often ...

, but this is disputed by Petrov. Associated minerals include

metavivianite Metavivianite () is a hydrated iron phosphate mineral found in a number of geological environments. As a secondary mineral it is typically formed from oxidizing vivianite. Metavivianite is typically found as dark blue or dark green prismatic to f ...

, ludlamite,

pyrite The mineral pyrite (), or iron pyrite, also known as fool's gold, is an iron sulfide with the chemical formula Fe S2 (iron (II) disulfide). Pyrite is the most abundant sulfide mineral. Pyrite's metallic luster and pale brass-yellow hue giv ...

siderite Siderite is a mineral composed of iron(II) carbonate (FeCO3). It takes its name from the Greek word σίδηρος ''sideros,'' "iron". It is a valuable iron mineral, since it is 48% iron and contains no sulfur or phosphorus. Zinc, magnesium an ...

and

pyrrhotite Pyrrhotite is an iron sulfide mineral with the formula Fe(1-x)S (x = 0 to 0.2). It is a nonstoichiometric variant of FeS, the mineral known as troilite. Pyrrhotite is also called magnetic pyrite, because the color is similar to pyrite and it ...

. Hydrothermal veins produce the best crystal specimens with the classic gemmy green color. The type locality is Wheal Kind (Wheal Kine), West Wheal Kitty group, St Agnes, St Agnes District, Cornwall, England.

Oxidation

Oxidation of vivianite is an internal process; no oxygen or water enters or leaves the mineral from the outside. A visible light

photon A photon () is an elementary particle that is a quantum of the electromagnetic field, including electromagnetic radiation such as light and radio waves, and the force carrier for the electromagnetic force. Photons are Massless particle, massless ...

knocks a proton out of a water molecule leaving a

hydroxide ion Hydroxide is a diatomic anion with chemical formula OH−. It consists of an oxygen and hydrogen atom held together by a single covalent bond, and carries a negative electric charge. It is an important but usually minor constituent of water. I ...

(OH⁻). In turn a divalent iron Fe²⁺ loses an electron to become Fe³⁺, i.e., it is

oxidized Redox (reduction–oxidation, , ) is a type of chemical reaction in which the oxidation states of substrate change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is the gain of electrons or a de ...

and balances the charge. This process starts when visible light falls on the vivianite, and it can occur within a few minutes, drastically changing the color of the mineral. Eventually the vivianite changes to a new species, metavivianite Fe²⁺₂Fe³⁺(PO₄)₂(OH)·(H₂O)₇, which usually occurs as paramorphs after vivianite.

Pigment

Vivianite was known as a pigment since Roman times but its use in oil painting was rather limited. It has been found in Vermeer's '' The Procuress'' in the blue-grey parts of the carpet in the foreground. Jan Vermeer van Delft 002

Localities

* Brazil. Cigana Mine, Galileia, Minas Gerais, with muscovite and pyrite.The Mineralogical Record (2004) 35-2:156 Typically wedge-shaped crystals of vivianite to 11 cm across, of medium lustre, smoke-blue color and good transparency on matrix of sharp silvery

muscovite Muscovite (also known as common mica, isinglass, or potash mica) is a hydrated phyllosilicate mineral of aluminium and potassium with formula K Al2(Al Si3 O10)( F,O H)2, or ( KF)2( Al2O3)3( SiO2)6( H2O). It has a highly perfect basal cleavage ...

plates, some with

druses The Druze (; ar, دَرْزِيٌّ, ' or ', , ') are an Arabic-speaking esoteric ethnoreligious group from Western Asia who adhere to the Druze faith, an Abrahamic, monotheistic, syncretic, and ethnic religion based on the teachings of ...

microcrystals.The Mineralogical Record (2004) 35-3:252 * Bolivia: Llallagua, Potosi: Crystals to 10 cm at the Siglio XX mine. Transparent bottle green crystals to 10 cm from the San Jose/San Firmin vein. In general the vivianite occurs as

crystals on a matrix of

botryoidal A botryoidal ( ) texture or mineral habit, is one in which the mineral has an external form composed of many rounded segments, named for the Ancient Greek (), meaning "a bunch of grapes".Adjective form: ''botruoeidēs'' This is a common form f ...

goethite Goethite (, ) is a mineral of the diaspore group, consisting of iron(III) oxide-hydroxide, specifically the "α" polymorph. It is found in soil and other low-temperature environments such as sediment. Goethite has been well known since ancient ...

derived from the alteration of

and

marcasite The mineral marcasite, sometimes called “white iron pyrite”, is iron sulfide (FeS2) with orthorhombic crystal structure. It is physically and crystallographically distinct from pyrite, which is iron sulfide with cubic crystal structure. Bot ...

. Specimens found in 2000 were associated with childrenite, cronstedtite,

franckeite Franckeite, chemical formula Pb5Sn3Sb2S14, belongs to a family of complex sulfide minerals. Franckeite is a sulfosalt. It is closely related to cylindrite. It was first described in 1893 for an occurrence in Chocaya, Potosí Department, Bolivia. ...

and pink massive

sphalerite Sphalerite (sometimes spelled sphaelerite) is a sulfide mineral with the chemical formula . It is the most important ore of zinc. Sphalerite is found in a variety of deposit types, but it is primarily in sedimentary exhalative, Mississippi-Va ...

.The Mineralogical Record (2006) 37-2:156 * Cameroon: The world's largest vivianite crystals (more than a meter long) from mud. * Canada: In

at Côte St Charles, Vaudreuil-Soulanges, Montérégie, Québec. * Germany: In the

limonite Limonite () is an iron ore consisting of a mixture of hydrated iron(III) oxide-hydroxides in varying composition. The generic formula is frequently written as FeO(OH)·H2O, although this is not entirely accurate as the ratio of oxide to hydrox ...

ores in

Amberg Amberg () is a town in Bavaria, Germany. It is located in the Upper Palatinate, roughly halfway between Regensburg and Bayreuth. In 2020, over 42,000 people lived in the town. History The town was first mentioned in 1034, at that time under t ...

Auerbach Auerbach, German for "meadow-brook", may refer to the following: Places In Austria *Auerbach, Upper Austria, Braunau am Inn district In Germany Places: *Auerbach (Albtal), a village of Karlsbad, administrative area in Baden-Württemberg * Auerb ...

and in the pegmatites of Hagendorf, Bavaria. * Japan: At Nagasawa, Iwama-machi,

Ibaraki Prefecture is a prefecture of Japan located in the Kantō region of Honshu. Ibaraki Prefecture has a population of 2,871,199 (1 June 2019) and has a geographic area of . Ibaraki Prefecture borders Fukushima Prefecture to the north, Tochigi Prefectur ...

, vivianite was found along fractures in rocks rich in

graphite Graphite () is a crystalline form of the element carbon. It consists of stacked layers of graphene. Graphite occurs naturally and is the most stable form of carbon under standard conditions. Synthetic and natural graphite are consumed on la ...

and

. The vivianite is intimately associated with pyrite and occurs as very thin tabular crystals, up to 10 cm in length. * Kosovo.

Trepča Mines The Trepča Mines ( al, Miniera e Trepçës, sr, Рудник Трепча / ''Rudnik Trepča'') is a large industrial complex in Kosovo, located northeast of Mitrovica. The mine is located on the southern slopes of the Kopaonik mountain, bet ...

, Stari Trg. Thick prismatic crystals up to 10 cm long and 2 cm thick, relatively stable. Deep green in color and transparent, commonly resting on

, and in some cases on

quartz Quartz is a hard, crystalline mineral composed of silica ( silicon dioxide). The atoms are linked in a continuous framework of SiO4 silicon-oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical ...

carbonates A carbonate is a salt of carbonic acid (H2CO3), characterized by the presence of the carbonate ion, a polyatomic ion with the formula . The word ''carbonate'' may also refer to a carbonate ester, an organic compound containing the carbonate ...

.The Mineralogical Record (2007) 38-4:290 * Mexico: In blue-green gem quality crystals to 8 cm at the San Antonio Mine,

Santa Eulalia, Chihuahua Santa Eulalia is a town and seat of the municipality of Aquiles Serdán, in the northern Mexican state of Chihuahua. In 2010, the town had a population of 7,135, up from 2,089 in 2005. Founded in 1652 by Diego del Castillo Diego is a Spa ...

. * Russia: In

sedimentary Sedimentary rocks are types of rock that are formed by the accumulation or deposition of mineral or organic particles at Earth's surface, followed by cementation. Sedimentation is the collective name for processes that cause these particles ...

iron ores and in fossil shells in the

Kerch Kerch ( uk, Керч; russian: Керчь, ; Old East Slavic: Кърчевъ; Ancient Greek: , ''Pantikápaion''; Medieval Greek: ''Bosporos''; crh, , ; tr, Kerç) is a city of regional significance on the Kerch Peninsula in the east of ...

and

Taman peninsula The Taman Peninsula (russian: Тама́нский полуо́стров, ''Tamanskiy poluostrov'') is a peninsula in the present-day Krasnodar Krai of Russia, which borders the Sea of Azov to the North, the Strait of Kerch to the West and the ...

on the

Black Sea The Black Sea is a marginal mediterranean sea of the Atlantic Ocean lying between Europe and Asia, east of the Balkans, south of the East European Plain, west of the Caucasus, and north of Anatolia. It is bounded by Bulgaria, Georgia, ...

. *Spain: At the Brunita mine, Cartagena, Murcia, vivianite was found as deep green crystals, up to 8 cm * USA: In

diatomite Diatomaceous earth (), diatomite (), or kieselgur/kieselguhr is a naturally occurring, soft, siliceous sedimentary rock that can be crumbled into a fine white to off-white powder. It has a particle size ranging from more than 3 μm to les ...

in a

tertiary Tertiary ( ) is a widely used but obsolete term for the geologic period from 66 million to 2.6 million years ago. The period began with the demise of the non- avian dinosaurs in the Cretaceous–Paleogene extinction event, at the start ...

lake bed near Burey,

Shasta County, California Shasta County (), officially the County of Shasta, is a county in the northern portion of the U.S. state of California. Its population is 182,155 as of the 2020 census, up from 177,223 from the 2010 census. The county seat is Redding. Shasta ...

. * USA: In green sand at Middletown, New Castle County, Delaware. * USA: Blackbird Mine, Lemhi County, Idaho. Crystals in shades of pink, green, greyish blue, purple and purplish black, as well as colorless. The unique deep purple color of some Blackbird mine specimens is characteristic of the locality. Some single crystals have both purple and green zones. Vivianite crystals from the Blackbird Mine are usually elongated and blade-like. They occur as singles and groups on dark altered

schist Schist ( ) is a medium-grained metamorphic rock showing pronounced schistosity. This means that the rock is composed of mineral grains easily seen with a low-power hand lens, oriented in such a way that the rock is easily split into thin flakes ...

and on white

. Associated minerals include ludlamite,

and

.The Mineralogical Record (2010) 41-4:366 * USA: Abundant in the pegmatites of

Newry, Maine Newry (; ) is a resort town in Oxford County, Maine, United States. The population was 411 at the 2020 census. Newry was the site of one of Maine's worst Cold War aircraft crashes. The town is the home of Sunday River Ski Resort and has a pr ...

. * New Zealand: Small amounts of vivianite are present within the sediments of Lake Kohangapiripiri.Cochran, U., Goff, J., Hannah, M., and Hull, A. (1999) Relative stability on a tectonically active coast: paleoenvironment during the last 7000 years at Lake Kohangapiripiri, Wellington, New Zealand, ''Quaternary International'', 56, 53–63

References

{{Authority control Iron(II) minerals Phosphate minerals Monoclinic minerals Minerals in space group 10 Vivianite group