Whiteite is a rare

hydrated Drinking is the act of ingesting water or other liquids into the body through the mouth, proboscis, or elsewhere. Humans drink by swallowing, completed by peristalsis in the esophagus. The physiological processes of drinking vary widely among o ...

hydroxyphosphate mineral.

Whiteite subgroup

The name whiteite refers to three minerals in the jahnsite-whiteite group, whiteite subgroup. Subgroup members (formulae from IMA): *Whiteite-(CaFeMg), IMA1975-001, CaFe²⁺Mg₂Al₂(PO₄)₄(OH)₂·8H₂O *Whiteite-(MnFeMg), IMA1978-A, Mn²⁺Fe²⁺Mg₂Al₂(PO₄)₄(OH)₂·8H₂O *Whiteite-(CaMnMg), IMA1986-012, CaMn²⁺Mg₂Al₂(PO₄)₄(OH)₂·8H₂O *Rittmannite, Mn²⁺Mn²⁺Fe²⁺₂Al₂(PO₄)₄(OH)₂·8H₂O In the whiteite formulae, the symbols in brackets indicate the dominant atom in three distinct structural positions, designated X, M(1), and M(2), in that order; for instance,

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 ta ...

Mg is always the dominant atom in the M(2) position for all the whiteite minerals. Whiteite was named after John Sampson White Jr (born 1933), associate curator of minerals at the

Smithsonian Institution The Smithsonian Institution ( ), or simply the Smithsonian, is a group of museums and education and research centers, the largest such complex in the world, created by the U.S. government "for the increase and diffusion of knowledge". Founded ...

, and founder, editor and publisher (1970-1982) of the Mineralogical Record.

Unit cell

All members of the series belong to the

monoclinic crystal system 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 ...

with point group 2/m. Most sources give the

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 uncha ...

as P2₁/a for the Ca Fe rich member, which was the first of the series to be described, but Dana gives it as P2/a. The other members are variously described in different sources as having space groups P2₁/a, P2/a or Pa.
There are 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 necessaril ...

(Z = 2). The cell parameters vary slightly between the group members, but to the nearest

angstrom The angstromEntry "angstrom" in the Oxford online dictionary. Retrieved on 2019-03-02 from https://en.oxforddictionaries.com/definition/angstrom.Entry "angstrom" in the Merriam-Webster online dictionary. Retrieved on 2019-03-02 from https://www.m ...

they all have a = 15 Å, b = 7 Å and c = 10 Å, with β 112.5 to 113.4. Individual values are: *Whiteite-(CaFeMg) a = 14.90 Å, b = 6.98 Å, c = 10.13 Å, β = 113.12 *Whiteite-(MnFeMg) a = 14.99 Å, b = 6.96 Å, c = 10.14 Å, β = 113.32 *Whiteite-(CaMnMg) a = 14.842 Å, b = 6.976 Å, c = 10.109 Å, β = 112.59

Appearance

The whiteite minerals are generally brown, pink or yellow, and whiteite-(CaMnMg) may also be light lavender coloured. They are transparent to translucent, with a vitreous luster and a white to brownish white streak. They occur as aggregates of tabular crystals, or thick tabular canoe-shaped crystals. Whiteite from Rapid Creek in the

Yukon Yukon (; ; formerly called Yukon Territory and also referred to as the Yukon) is the smallest and westernmost of Canada's three territories. It also is the second-least populated province or territory in Canada, with a population of 43,964 as ...

, Canada, is often associated with deep blue

lazulite Lazulite () is a blue, phosphate mineral containing magnesium, iron, and aluminium phosphate. Lazulite forms one endmember of a solid solution series with the darker iron rich scorzalite. Lazulite crystallizes in the monoclinic system. Crystal ...

crystals (33 out of 49 photos on Mindat.org).

Optical properties

The optical class is thought to be biaxial (+), but whiteite-(CaFeMg) may be biaxial (-). The

refractive indices In optics, the refractive index (or refraction index) of an optical medium is a dimensionless number that gives the indication of the light bending ability of that medium. The refractive index determines how much the path of light is bent, or ...

are N_x = 1.580, N_y = 1.584 to 1.585 and N_z = 1.590 to 1.591, similar to those for

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 ...

Physical properties

Whiteite is invariably twinned, giving the crystals a pseudo- orthorhombic appearance, and the cleavage is good to perfect. Whiteite is quite soft, with

hardness In materials science, hardness (antonym: softness) is a measure of the resistance to localized plastic deformation induced by either mechanical indentation or abrasion. In general, different materials differ in their hardness; for example hard ...

3 to 4, between calcite and

fluorite Fluorite (also called fluorspar) is the mineral form of calcium fluoride, CaF2. It belongs to the halide minerals. It crystallizes in isometric cubic habit, although octahedral and more complex isometric forms are not uncommon. The Mohs sca ...

. Its

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 at its densest ...

is 2.58, similar to that of

. Whiteite is not radioactive.

Occurrence

The type locality for whiteite-(CaFeMg)and whiteite-(MnFeMg) is the Ilha claim, Taquaral, Itinga, Jequitinhonha valley, Minas Gerais, Brazil, and for whiteite-(CaMnMg) it is the Tip Top Mine (Tip Top pegmatite), Fourmile, Custer District,

Custer County, South Dakota Custer County is a county in the U.S. state of South Dakota. As of the 2020 United States Census, the population was 8,318. Its county seat is Custer. The county was created in 1875, and was organized in 1877. Geography Custer County lies on t ...

, US. The type material is conserved at the National School of Mines, Paris, France, and at the

National Museum of Natural History The National Museum of Natural History is a natural history museum administered by the Smithsonian Institution, located on the National Mall in Washington, D.C., United States. It has free admission and is open 364 days a year. In 2021, with 7 ...

, Washington DC, US, reference 123013. At the Lavra da Ilha pegmatite, Taquaral, Brazil, whiteite is found in a complex zoned

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 under ...

pegmatite associated with eosphorite, zanazziite,

wardite Wardite is a hydrous sodium aluminium phosphate hydroxide mineral with formula: Na Al3( P O4)2(O H)4·2( H2O). Wardite is of interest for its rare crystallography. It crystallizes in the tetragonal trapezohedral class and is one of only a few ...

albite Albite is a plagioclase feldspar mineral. It is the sodium endmember of the plagioclase solid solution series. It represents a plagioclase with less than 10% anorthite content. The pure albite endmember has the formula . It is a tectosilicate ...

and

. At Blow River, the

, Canada, it is found in iron-rich

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 ...

rocks with

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 and ...

, arrojadite and

. At Ilha de Taquaral, Minas Gerais, Brazil, it occurs along

joints A joint or articulation (or articular surface) is the connection made between bones, ossicles, or other hard structures in the body which link an animal's skeletal system into a functional whole.Saladin, Ken. Anatomy & Physiology. 7th ed. McGraw- ...

and

fractures Fracture is the separation of an object or material into two or more pieces under the action of stress. The fracture of a solid usually occurs due to the development of certain displacement discontinuity surfaces within the solid. If a displa ...

and

associated with other

phosphates 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 ...

References

{{Reflist Phosphate minerals Calcium minerals Iron(II) minerals Magnesium minerals Manganese(II) minerals Monoclinic minerals Minerals in space group 13