Whiteite

Whiteite with lazulite from Rapid Creek, Dawson Mining District, the Yukon, Canada

General
Category| Phosphate minerals
Formula
(repeating unit)| Whiteite-(CaFeMg):

CaFe2+Mg2Al2(PO4)4(OH)2·8H2O
Whiteite-(MnFeMg):
Mn2+Fe2+Mg2Al2(PO4)4(OH)2·8H2O
Whiteite-(CaMnMg):

CaMn2+Mg2Al2(PO4)4(OH)2·8H2O
Strunz classification| 8.DH.15 (10 ed, whole series)
7/D.29 (8 ed)
Dana classification| 42.11.3.1 Whiteite-(CaFeMg)

42.11.3.2 Whiteite-(MnFeMg)

42.11.3.3 Whiteite-(CaMnMg)
Crystal system| Monoclinic
Crystal class| Prismatic (2/m)
(same H-M symbol)
Space group| P2/a (no. 13)
Identification
Formula mass| Whiteite-(CaFeMg):756.29g

Whiteite-(MnFeMg):767.44g

Whiteite-(CaMnMg):755.61g
Color| Whiteite-(CaFeMg): Brown, pink-brown or yellow

Whiteite-(MnFeMg): Brown

Whiteite-(CaMnMg): Yellow, light lavender or pink
Crystal 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 scale hardness| 3 to 4
|re|er}}| Vitreous
Streak| White to brownish white
Diaphaneity| Translucent to transparent
Specific gravity| Whiteite-(CaFeMg) 2.58

Whiteite-(MnFeMg)2.67

Whiteite-(CaMnMg)2.63
Optical properties| Biaxial (+)
Refractive index| Nx = 1.580, Ny = 1.584 to 1.585, Nz = 1.590 to 1.591
Other characteristics| Not radioactive
References| [1][2][3][4][5][6][7][8][9]

Whiteite is a rare hydrated hydroxyphosphate mineral.

## Contents

* 1 Whiteite subgroup
* 2 Unit cell
* 3 Appearance
* 4 Optical properties
* 5 Physical properties
* 6 Occurrence
* 7 References

## Whiteite subgroup

The name whiteite refers to three minerals in the jahnsite-whiteite group, whiteite subgroup. Subgroup members (formulae from IMA[8]):

* 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.[5] Whiteite was named after John Sampson White Jr (born 1933),[10] associate curator of minerals at the Smithsonian Institution, and founder, editor and publisher (1970–1982) of the Mineralogical Record.[11]

## 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,[6][2][5] but Dana gives it as P2/a.[1] 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 (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:[1][2][3][4][5][6]

* 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.[5] 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.[1] 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 (+),[7][2][3][4] but whiteite-(CaFeMg) may be biaxial (−).[5][6] The refractive indices are Nx = 1.580, Ny = 1.584 to 1.585 and Nz = 1.590 to 1.591, similar to those for quartz.

## Physical properties

Whiteite is invariably twinned, giving the crystals a pseudo-orthorhombic appearance,[1][5] and the cleavage is good to perfect.[5] Whiteite is quite soft, with hardness 3 to 4, between calcite and fluorite. Its specific gravity is 2.58, similar to that of quartz.[1][2][3][4][5][6] Whiteite is not radioactive.[2][3][4]

## 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.[7] 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.[5]

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.[5] At Blow River, the Yukon, Canada, it is found in iron-rich sedimentary rocks with siderite, lazulite, arrojadite and quartz.[5] At Ilha de Taquaral, Minas Gerais, Brazil, it occurs along joints and fractures in quartz and albite associated with other phosphates.[6]

## References

1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 Gaines et al (1997) Dana's New Mineralogy Eighth Edition. Wiley
2. ↑ 2.0 2.1 2.2 2.3 2.4 2.5 "Whiteite-(CaFeMg) Mineral Data". Webmineral.com. http://www.webmineral.com/data/Whiteite-(CaFeMg).shtml. Retrieved 2012-03-15.
3. ↑ 3.0 3.1 3.2 3.3 3.4 "Whiteite-(MnFeMg) Mineral Data". Webmineral.com. http://www.webmineral.com/data/Whiteite-(MnFeMg).shtml. Retrieved 2012-03-15.
4. ↑ 4.0 4.1 4.2 4.3 4.4 "Whiteite-(CaMnMg) Mineral Data". Webmineral.com. http://www.webmineral.com/data/Whiteite-(CaMnMg).shtml. Retrieved 2012-03-15.
5. ↑ 5.00 5.01 5.02 5.03 5.04 5.05 5.06 5.07 5.08 5.09 5.10 5.11 "Handbook of Mineralogy". Handbook of Mineralogy. http://www.handbookofmineralogy.org. Retrieved 2012-03-15.
6. ↑ 6.0 6.1 6.2 6.3 6.4 6.5 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]
7. ↑ 7.0 7.1 7.2 "Whiteite-(CaFeMg): Whiteite-(CaFeMg) mineral information and data". Mindat.org. 2012-01-30. http://www.mindat.org/min-4277.html. Retrieved 2012-03-15.
8. ↑ 8.0 8.1 "IMA Mineral List with Database of Mineral Properties". Rruff.info. http://rruff.info/ima. Retrieved 2012-03-15.
9. ↑ Elliott, Peter; Willis, Anthony C. (1 March 2019). "Whiteite-(mnmnmg), a New Jahnsite-Group Mineral from Iron Monarch, South Australia: Description and Crystal Structure". The Canadian Mineralogist 57 (2): 215–223. doi:10.3749/canmin.1800070. Bibcode: 2019CaMin..57..215E.
10. ↑ "Label Archive". The Mineralogical Record. 1933-09-30. http://www.mineralogicalrecord.com/labels.asp?colid=606. Retrieved 2012-03-15.
11. ↑ "The Mineralogical Record". The Mineralogical Record. http://www.mineralogicalrecord.com. Retrieved 2012-03-15.

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