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Pickeringite

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John Pickering
Formula:
MgAl2(SO4)4 · 22H2O
Colour:
Colourless to white, light yellow, pale pink, gray; colourless in transmitted light
Lustre:
Vitreous
Hardness:
1½ - 2
Specific Gravity:
1.73 - 1.79
Crystal System:
Monoclinic
Name:
For John Pickering (February 7, 1777 Salem - May 5, 1846 Boston), American linguist and philologist.
Halotrichite Group; Halotrichite-Pickeringite Series.
The Mg analogue of Halotrichite.

At least a partial series entends toward Apjohnite.




Classification of Pickeringite

Approved, 'Grandfathered' (first described prior to 1959)
7.CB.85

7 : SULFATES (selenates, tellurates, chromates, molybdates, wolframates)
C : Sulfates (selenates, etc.) without additional anions, with H2O
B : With only medium-sized cations
29.7.3.1

29 : HYDRATED ACID AND NORMAL SULFATES
7 : AB2(XO4)4·H2O
25.3.18

25 : Sulphates
3 : Sulphates of Mg

Physical Properties of Pickeringite

Vitreous
Transparency:
Translucent
Colour:
Colourless to white, light yellow, pale pink, gray; colourless in transmitted light
Hardness:
1½ - 2 on Mohs scale
Tenacity:
Brittle
Cleavage:
Poor/Indistinct
On {010} poor.
Fracture:
Conchoidal
Density:
1.73 - 1.79 g/cm3 (Measured)    1.84 g/cm3 (Calculated)
Comment:
Pure end-member values.

Optical Data of Pickeringite

Type:
Biaxial (-)
RI values:
nα = 1.475 nβ = 1.480 nγ = 1.483
2V:
Measured: 60° , Calculated: 80°
Max Birefringence:
δ = 0.008
Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
Surface Relief:
Moderate
Dispersion:
none

Chemical Properties of Pickeringite

Formula:
MgAl2(SO4)4 · 22H2O
Common Impurities:
Mn,Fe,Co

Crystallography of Pickeringite

Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Space Group:
P21/b
Setting:
P21/c
Cell Parameters:
a = 20.8 Å, b = 24.2 Å, c = 6.18 Å
β = 95°
Ratio:
a:b:c = 0.86 : 1 : 0.255
Unit Cell V:
3,098.93 ų (Calculated from Unit Cell)
Z:
4
Morphology:
Crystals acicular [001]; distinctly terminated crystals rare. Radial or matted aggregates of hair-like crystals; tufted; spheroidal; as incrustations or effloresences; asbestiform. Larger crystals may be hollow or contain bubbles of liquid or gas.

X-Ray Powder Diffraction

Image Loading

Radiation - Copper Kα
Data Set:
Data courtesy of RRUFF project at University of Arizona, used with permission.
Powder Diffraction Data:
d-spacingIntensity
6.08 (20)
4.97 (20)
4.82 (100)
4.32 (35)
4.122 (30)
3.510 (90)
3.791 (30)
Comments:
ICDD 12-299.

Type Occurrence of Pickeringite

Synonyms of Pickeringite

Other Language Names for Pickeringite

Varieties of Pickeringite

Ferropickeringite

An iron-rich variety of pickeringite.
Originally reported from Dientnergraben, Eschenau, Lend, Schwarzach, Salzburg, Austria.

Kasparite

A cobaltoan variety of Pickeringite.
Originally described from Dubník, Červenica (Czerwenitza), Northern Slanské Mts, Presov Region, Slovak Republic.

Manganoan Pickeringite

Mn'' may substitute for (Mg,Fe) in at least a partial series toward Apjohnite.

Relationship of Pickeringite to other Species

Other Members of this group:
ApjohniteMn2+Al2(SO4)4 · 22H2O
BíliniteFe2+Fe3+2(SO4)4 · 22H2O
Dietrichite(Zn,Fe2+,Mn2+)Al2(SO4)4 · 22H2O
HalotrichiteFeAl2(SO4)4 · 22H2O
Redingtonite(Fe2+,Mg,Ni)(Cr,Al)2(SO4)4·22H2O
Wupatkiite(Co,Mg,Ni)Al2(SO4)4·22H2O
Forms a series with:

Common Associates

Associated Minerals Based on Photo Data:
Kasparite8 photos of Pickeringite associated with Kasparite on mindat.org.
Melanterite6 photos of Pickeringite associated with Melanterite on mindat.org.
Botryogen5 photos of Pickeringite associated with Botryogen on mindat.org.
Fibroferrite4 photos of Pickeringite associated with Fibroferrite on mindat.org.
Chalcanthite4 photos of Pickeringite associated with Chalcanthite on mindat.org.
Copiapite4 photos of Pickeringite associated with Copiapite on mindat.org.
Halotrichite3 photos of Pickeringite associated with Halotrichite on mindat.org.
Cuprian Melanterite3 photos of Pickeringite associated with Cuprian Melanterite on mindat.org.
Magnesiocopiapite3 photos of Pickeringite associated with Magnesiocopiapite on mindat.org.
Slavíkite3 photos of Pickeringite associated with Slavíkite on mindat.org.

Related Minerals - Nickel-Strunz Grouping

7.CB.05Dwornikite(Ni,Fe)SO4 · H2O
7.CB.05GunningiteZnSO4 · H2O
7.CB.05KieseriteMgSO4 · H2O
7.CB.05Poitevinite(Cu,Fe,Zn)SO4 · H2O
7.CB.05SzmikiteMnSO4 · H2O
7.CB.05SzomolnokiteFeSO4 · H2O
7.CB.05CobaltkieseriteCoSO4 · H2O
7.CB.07SanderiteMgSO4 · 2H2O
7.CB.10BonattiteCuSO4 · 3H2O
7.CB.15Aplowite(Co,Mn,Ni)SO4 · 4H2O
7.CB.15Boyleite(Zn,Mg)SO4 · 4H2O
7.CB.15Ilesite(Mn,Zn,Fe)SO4 · 4H2O
7.CB.15RozeniteFeSO4 · 4H2O
7.CB.15StarkeyiteMgSO4 · 4H2O
7.CB.15DrobeciteCdSO4 · 4H2O
7.CB.15CranswickiteMgSO4 · 4H2O
7.CB.20ChalcanthiteCuSO4 · 5H2O
7.CB.20JôkokuiteMnSO4 · 5H2O
7.CB.20PentahydriteMgSO4 · 5H2O
7.CB.20SiderotilFeSO4 · 5H2O
7.CB.25Bianchite(Zn,Fe)SO4 · 6H2O
7.CB.25Chvaleticeite(Mn,Mg)SO4 · 6H2O
7.CB.25FerrohexahydriteFeSO4 · 6H2O
7.CB.25HexahydriteMgSO4 · 6H2O
7.CB.25Moorhouseite(Co,Ni,Mn)SO4 · 6H2O
7.CB.25Nickelhexahydrite(Ni,Mg,Fe)SO4 · 6H2O
7.CB.30RetgersiteNiSO4 · 6H2O
7.CB.35BieberiteCoSO4 · 7H2O
7.CB.35BoothiteCuSO4 · 7H2O
7.CB.35MallarditeMnSO4 · 7H2O
7.CB.35MelanteriteFeSO4 · 7H2O
7.CB.35Zincmelanterite(Zn,Cu,Fe)SO4 · 7H2O
7.CB.35Alpersite(Mg,Cu)[SO4] · 7H2O
7.CB.40EpsomiteMgSO4 · 7H2O
7.CB.40GoslariteZnSO4 · 7H2O
7.CB.40MorenositeNiSO4 · 7H2O
7.CB.45AlunogenAl2(SO4)3 · 17H2O
7.CB.45Meta-alunogenAl2(SO4)3 · 12H2O
7.CB.50AluminocoquimbiteFeAl(SO4)3 · 9H2O
7.CB.55CoquimbiteFe2-xAlx(SO4)3 · 9H2O, x ~0.5
7.CB.55ParacoquimbiteFe2(SO4)3 · 9H2O
7.CB.55Rhomboclase(H5O2)Fe3+(SO4)2 · 2H2O
7.CB.60KorneliteFe2(SO4)3 · 7H2O
7.CB.65QuenstedtiteFe2(SO4)3 · 11H2O
7.CB.70LauseniteFe2(SO4)3·5H2O
7.CB.75LishizheniteZnFe2(SO4)4 · 14H2O
7.CB.75RömeriteFe2+Fe3+2(SO4)4 · 14H2O
7.CB.80RansomiteCuFe2(SO4)4 · 6H2O
7.CB.85ApjohniteMn2+Al2(SO4)4 · 22H2O
7.CB.85BíliniteFe2+Fe3+2(SO4)4 · 22H2O
7.CB.85Dietrichite(Zn,Fe2+,Mn2+)Al2(SO4)4 · 22H2O
7.CB.85HalotrichiteFeAl2(SO4)4 · 22H2O
7.CB.85Redingtonite(Fe2+,Mg,Ni)(Cr,Al)2(SO4)4·22H2O
7.CB.85Wupatkiite(Co,Mg,Ni)Al2(SO4)4·22H2O
7.CB.90MeridianiiteMgSO4 · 11H2O

Related Minerals - Hey's Chemical Index of Minerals Grouping

25.3.1KieseriteMgSO4 · H2O
25.3.2SanderiteMgSO4 · 2H2O
25.3.3StarkeyiteMgSO4 · 4H2O
25.3.4PentahydriteMgSO4 · 5H2O
25.3.5HexahydriteMgSO4 · 6H2O
25.3.6EpsomiteMgSO4 · 7H2O
25.3.7CaminiteMg7(SO4)5(OH)4 · H2O
25.3.8VanthoffiteNa6Mg(SO4)4
25.3.9BlöditeNa2Mg(SO4)2 · 4H2O
25.3.10KonyaiteNa2Mg(SO4)2 · 5H2O
25.3.11LöweiteNa12Mg7(SO4)13 · 15H2O
25.3.12UklonskoviteNaMg(SO4)F · 2H2O
25.3.13LangbeiniteK2Mg2(SO4)3
25.3.14LeoniteK2Mg(SO4)2 · 4H2O
25.3.15PicromeriteK2Mg(SO4)2 · 6H2O
25.3.16Efremovite(NH4)2Mg2(SO4)3
25.3.17Boussingaultite(NH4)2Mg(SO4)2 · 6H2O

Related Minerals - Dana Grouping (8th Ed.)

29.7.3.2HalotrichiteFeAl2(SO4)4 · 22H2O
29.7.3.3ApjohniteMn2+Al2(SO4)4 · 22H2O
29.7.3.4Dietrichite(Zn,Fe2+,Mn2+)Al2(SO4)4 · 22H2O
29.7.3.5BíliniteFe2+Fe3+2(SO4)4 · 22H2O
29.7.3.6Redingtonite(Fe2+,Mg,Ni)(Cr,Al)2(SO4)4·22H2O
29.7.3.7Wupatkiite(Co,Mg,Ni)Al2(SO4)4·22H2O

Other Information

Notes:
Soluble in H2O, astringent taste.
Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

References for Pickeringite

Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Hayes A A (1844) Description and analysis of pickeringite, a native magnesian alum. American Journal of Science and Arts 46, 360-362
Dana, J.D. (1868) System of Mineralogy, 5th. Edition, New York: 654 (as Bosjemanite).
Roster (1876) Boll. com. geol. Ital.: 302 (as Picroallumogene).
Goldsmith, E. (1877), On sonomaite: Acad. Nat. Sci. Philadelphia Proc.: 28: 263-264.
Doelter (1882) Vulk. Gesteine und Min. der Capverde Inseln: 93 (as Dumreicherit).
Darapsky (1887) Neues Jahrbuch für Mineralogie, Geologie und Paleontologie, Heidelberg, Stuttgart: I: 131 (as Sesqui-Magnesia-alaun).
Darapsky (1890) Neues Jahrbuch für Mineralogie, Geologie und Paleontologie, Heidelberg, Stuttgart: I: 49 (as Aromite).
Uhlig (1912) Centralblatt für Mineralogie, Geologie und Paleontologie, Stuttgart: 723.
Zsivy (1920) Zeitschrift für Kristallographie, Mineralogie und Petrographie, Leipzig: 55: 629.
Larsen, E.S. (1921) The Microscopic Determination of the Nonopaque Minerals, First edition, USGS Bulletin 679: 41.
Schairer and Lawson (1926) American Journal of Science: 11: 301.
Doelter, C. (1927) Handbuch der Mineral-chemie: 4 [2]: 523, 545.
Vavrinecz (1929) Magyar Chemiai Folyóirat, Budapest: 35: 1.
Hintze, Carl (1930) Handbuch der Mineralogie. Berlin and Leipzig. 6 volumes: 1 [3B]: 4505, 4512.
Kokta (1930) Přiroda, Brno: 32: 381.
Rutherford (1932) American Mineralogist: 17: 401.
Tokody (1933) Földtani Közlöny, Budapest (Magyarhone Földtani Torsulat): 62: 187.
Meixner and Pillewizer (1937) Zbl. Min.: 263.
Bandy (1938) American Mineralogist: 23: 724.
Gordon S G (1942) Results of the Chilean mineralogical expedition of 1938. Part VII.—The crystallography of alunogen, meta-alunogen and pickeringite. Notulae Naturae of The Academy of Natural Sciences of Philadelphia 101, 1-9
Palache, C., Berman, H., & Frondel, C. (1951), The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana, Yale University 1837-1892, Volume II. John Wiley and Sons, Inc., New York, 7th edition, revised and enlarged, 1124 pp.: 523-527.
Quartieri S, Triscari M, Viani A (2000) Crystal structure of the hydrated sulphate pickeringite (MgAl2(SO4)4·22H2O): X-ray powder diffraction study. European Journal of Mineralogy 12, 1131-1138

Internet Links for Pickeringite

mindat.org URL:
https://www.mindat.org/min-3204.html
Please feel free to link to this page.
Specimens:
The following Pickeringite specimens are currently listed for sale on minfind.com.

Localities for Pickeringite

Mineral and/or Locality  
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