Whiteite

{{Short description|Rare hydrated hydroxyphosphate mineral}} {{Infobox mineral | name = Whiteite | category = Phosphate minerals | boxwidth = 24 | boxbgcolor = | image = Whiteite-Lazulite-48334.jpg | caption = Whiteite with lazulite from Rapid Creek, Dawson Mining District, the Yukon, Canada | formula = Whiteite-(CaFeMg):<br/> CaFe²⁺Mg₂Al₂(PO₄)₄(OH)₂·8H₂O<br/> Whiteite-(MnFeMg):<br/> Mn²⁺Fe²⁺Mg₂Al₂(PO₄)₄(OH)₂·8H₂O<br/> Whiteite-(CaMnMg):<br/> CaMn²⁺Mg₂Al₂(PO₄)₄(OH)₂·8H₂O | molweight = Whiteite-(CaFeMg):756.29g<br/> Whiteite-(MnFeMg):767.44g<br/> Whiteite-(CaMnMg):755.61g | strunz = 8.DH.15 (10 ed, whole series) <br/><small>7/D.29 (8 ed)</small> | dana = 42.11.3.1 Whiteite-(CaFeMg) 42.11.3.2 Whiteite-(MnFeMg) 42.11.3.3 Whiteite-(CaMnMg) | system = Monoclinic | class = Prismatic (2/m) <br/><small>(same H-M symbol)</small> | symmetry = ''P2/a'' (no. 13) | color = Whiteite-(CaFeMg): Brown, pink-brown or yellow<br/> Whiteite-(MnFeMg): Brown<br/> Whiteite-(CaMnMg): Yellow, light lavender or pink | habit = Tabular crystals or aggregates thereof | twinning = Invariably twinned by reflection on {001} producing a pseudo-orthorhombic appearance | cleavage = On {001}. Poor for whiteite-(CaMnMg), but good for the other members of the series (HOM) | tenacity = Whiteite-(CaMnMg) is brittle (HOM) | mohs = 3 to 4 | luster = Vitreous | refractive = N_x = 1.580, N_y = 1.584 to 1.585, N_z = 1.590 to 1.591 | opticalprop = Biaxial (+) | streak = White to brownish white | gravity = Whiteite-(CaFeMg) 2.58<br/> Whiteite-(MnFeMg)2.67<br/> Whiteite-(CaMnMg)2.63 | diaphaneity = Translucent to transparent | other = Not radioactive | references = <ref name=Dana>Gaines et al (1997) Dana's New Mineralogy Eighth Edition. Wiley</ref><ref name=Webmin1>{{cite web|url=http://www.webmineral.com/data/Whiteite-(CaFeMg).shtml |title=Whiteite-(CaFeMg) Mineral Data |publisher=Webmineral.com |date= |accessdate=2012-03-15}}</ref><ref name=Webmin2>{{cite web|url=http://www.webmineral.com/data/Whiteite-(MnFeMg).shtml |title=Whiteite-(MnFeMg) Mineral Data |publisher=Webmineral.com |date= |accessdate=2012-03-15}}</ref><ref name=Webmin3>{{cite web|url=http://www.webmineral.com/data/Whiteite-(CaMnMg).shtml |title=Whiteite-(CaMnMg) Mineral Data |publisher=Webmineral.com |date= |accessdate=2012-03-15}}</ref><ref name=HOM>{{cite web|url=http://www.handbookofmineralogy.org |title=Handbook of Mineralogy |publisher=Handbook of Mineralogy |date= |accessdate=2012-03-15}}</ref><ref name=AM64>Fleischer, Chao and Pabst (1979) American Mineralogist 64:465, summarising Moore and Ito (1978) Mineralogical Magazine 42:309 [Whiteite-(CaMnMg) – AM75: Jambor and Grew (1990) American Mineralogist 75:933, summarising Grice, Dunn and Ramik (1989) The Canadian Mineralogist 27:699]</ref><ref name=Mindat>{{cite web|url=http://www.mindat.org/min-4277.html |title=Whiteite-(CaFeMg): Whiteite-(CaFeMg) mineral information and data |publisher=Mindat.org |date=2012-01-30 |accessdate=2012-03-15}}</ref><ref name=IMA>{{cite web|url=http://rruff.info/ima |title=IMA Mineral List with Database of Mineral Properties |publisher=Rruff.info |date= |accessdate=2012-03-15}}</ref><ref>{{cite journal |last1=Elliott |first1=Peter |last2=Willis |first2=Anthony C. |title=Whiteite-(mnmnmg), a New Jahnsite-Group Mineral from Iron Monarch, South Australia: Description and Crystal Structure |journal=The Canadian Mineralogist |date=1 March 2019 |volume=57 |issue=2 |pages=215–223 |doi=10.3749/canmin.1800070|bibcode=2019CaMin..57..215E |s2cid=133690952 }}</ref> }}

'''Whiteite''' is a rare hydrated hydroxyphosphate mineral.

==Whiteite subgroup== The name whiteite refers to three minerals in the jahnsite-whiteite group, whiteite subgroup. Subgroup members (formulae from IMA<ref name=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 Mg is always the dominant atom in the M(2) position for all the whiteite minerals.<ref name=HOM/> Whiteite was named after John Sampson White Jr (born 1933),<ref name=JSW>{{cite web |url=http://www.mineralogicalrecord.com/labels.asp?colid=606 |title=Label Archive |publisher=The Mineralogical Record |date=1933-09-30 |accessdate=2012-03-15 |archive-date=2020-07-28 |archive-url=https://web.archive.org/web/20200728093404/https://mineralogicalrecord.com/labels.asp?colid=606 |url-status=dead }}</ref> associate curator of minerals at the Smithsonian Institution, and founder, editor and publisher (1970–1982) of the Mineralogical Record.<ref name=Minrec>{{cite web|url=http://www.mineralogicalrecord.com |title=The Mineralogical Record |publisher=The Mineralogical Record |date= |accessdate=2012-03-15}}</ref>

==Unit cell== All members of the series belong to the monoclinic crystal system with point group 2/m. Most sources give the space group as P2₁/a for the Ca Fe rich member, which was the first of the series to be described,<ref name=AM64/><ref name=Webmin1/><ref name=HOM/> but Dana gives it as P2/a.<ref name=Dana/> The other members are variously described in different sources as having space groups P2₁/a, P2/a or Pa.<br />

There are two formula units per unit cell (Z = 2). The cell parameters vary slightly between the group members, but to the nearest angstrom they all have a = 15 Å, b = 7 Å and c = 10 Å, with β 112.5 to 113.4. Individual values are:<ref name=Dana/><ref name=Webmin1/><ref name=Webmin2/><ref name=Webmin3/><ref name=HOM/><ref name=AM64/> *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.<ref name=HOM/> 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.<ref name=Dana/> Whiteite from Rapid Creek in the Yukon, Canada, is often associated with deep blue lazulite crystals (33 out of 49 photos on Mindat.org).

==Optical properties== The optical class is thought to be biaxial (+),<ref name=Mindat/><ref name=Webmin1/><ref name=Webmin2/><ref name=Webmin3/> but whiteite-(CaFeMg) may be biaxial (−).<ref name=HOM/><ref name=AM64/> The refractive indices 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.

==Physical properties== Whiteite is invariably twinned, giving the crystals a pseudo-orthorhombic appearance,<ref name=Dana/><ref name=HOM/> and the cleavage is good to perfect.<ref name=HOM/> Whiteite is quite soft, with hardness 3 to 4, between calcite and fluorite. Its specific gravity is 2.58, similar to that of quartz.<ref name=Dana/><ref name=Webmin1/><ref name=Webmin2/><ref name = Webmin3/><ref name=HOM/><ref name=AM64/> Whiteite is not radioactive.<ref name=Webmin1/><ref name=Webmin2/><ref name = Webmin3/>

==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, US.<ref name=Mindat/> The type material is conserved at the National School of Mines, Paris, France, and at the National Museum of Natural History, Washington DC, US, reference 123013.<ref name=HOM/>

At the Lavra da Ilha pegmatite, Taquaral, Brazil, whiteite is found in a complex zoned granite pegmatite associated with eosphorite, zanazziite, wardite, albite and quartz.<ref name=HOM/> At Blow River, the Yukon, Canada, it is found in iron-rich sedimentary rocks with siderite, lazulite, arrojadite and quartz.<ref name=HOM/> At Ilha de Taquaral, Minas Gerais, Brazil, it occurs along joints and fractures in quartz and albite associated with other phosphates.<ref name=AM64/>

==References== {{Commons category|Whiteite}} {{Reflist}}

Category:Phosphate minerals Category:Calcium minerals Category:Iron(II) minerals Category:Magnesium minerals Category:Manganese(II) minerals Category:Monoclinic minerals Category:Minerals in space group 13