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Pickeringite

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Formula:
MgAl
 
2
(SO
 
4
)
 
4
· 22H
 
2
O
System:MonoclinicColour:Colourless to white, ...
Hardness:1½ - 2
Member of:Halotrichite Group
Name:For John Pickering (1777-1846), American linguist and philologist.


Halotrichite Group; Halotrichite-Pickeringite Series.

At least a partial series entends toward Apjohnite.

Mg analogue of Halotrichite.

Classification of Pickeringite

IMA status:Valid - first described prior to 1959 (pre-IMA) - "Grandfathered"
Strunz 8th edition ID:6/C.12-10
Nickel-Strunz 10th (pending) edition ID: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
Dana 8th edition ID:29.7.3.1

29 : HYDRATED ACID AND NORMAL SULFATES
7 : AB2(XO4)4·H2O
Hey's CIM Ref.:25.3.18

25 : Sulphates
3 : Sulphates of Mg
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Type Occurrence of Pickeringite

Type Locality:Cerros Pintados ("Cerro Pintados"), Pampa del Tamarugal, El Tamarugal Province, Tarapacá Region, Chile
Year of Discovery:1844

Physical Properties of Pickeringite

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

Crystallography of Pickeringite

Crystal System:Monoclinic
Class (H-M):2 - Sphenoidal
Space Group:P2
Cell Parameters:a = 20.8Å, b = 24.2Å, c = 6.18Å
β = 95°
Ratio:a:b:c = 0.86 : 1 : 0.255
Unit Cell Volume:V 3,098.93 ų (Calculated from Unit Cell)
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:
Horizontal Axis: ° to ° Vertical Axis: % Source Data: Filtered Data:
Data courtesy of RRUFF project at University of Arizona, used with permission.

Optical Data of Pickeringite

Type:Biaxial (-)
RI values: nα = 1.476 nβ = 1.480 nγ = 1.483
2V:Measured: 60° , Calculated: 80°
Maximum Birefringence:δ = 0.007

Chart 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:
MgAl
 
2
(SO
 
4
)
 
4
· 22H
 
2
O
Simplified for copy/paste:MgAl2(SO4)4·22H2O
Essential elements:Al, H, Mg, O, S
All elements listed in formula:Al, H, Mg, O, S
Analytical Data:
Completely soluble in water to an acid solution.
Common Impurities:Mn,Fe,Co

Relationship of Pickeringite to other Species

Series:Forms a series with Halotrichite (see here)
Member of:Halotrichite Group
Other Members of Group:

- +
Apjohnite
Mn
2+
 
Al
 
2
(SO
 
4
)
 
4
· 22H
 
2
O
Bílinite
Fe
2+
 
Fe
3+
2
(SO
 
4
)
 
4
· 22H
 
2
O
Dietrichite
(Zn,Fe
2+
 
,Mn
2+
 
)Al
 
2
(SO
 
4
)
 
4
· 22H
 
2
O
Halotrichite
FeAl
 
2
(SO
 
4
)
 
4
· 22H
 
2
O
Redingtonite
(Fe
2+
 
,Mg,Ni)(Cr,Al)
 
2
(SO
 
4
)
 
4
·22H
 
2
O
Wupatkiite
(Co,Mg,Ni)Al
 
2
(SO
 
4
)
 
4
·22H
 
2
O
Related Minerals - Nickel-Strunz Grouping):

- +
7.CB.05Dwornikite
(Ni,Fe)SO
 
4
· H
 
2
O
7.CB.05Gunningite
ZnSO
 
4
· H
 
2
O
7.CB.05Kieserite
MgSO
 
4
· H
 
2
O
7.CB.05Poitevinite
(Cu,Fe,Zn)SO
 
4
· H
 
2
O
7.CB.05Szmikite
MnSO
 
4
· H
 
2
O
7.CB.05Szomolnokite
FeSO
 
4
· H
 
2
O
7.CB.05Cobaltkieserite
CoSO
 
4
· H
 
2
O
7.CB.07Sanderite
MgSO
 
4
· 2H
 
2
O
7.CB.10Bonattite
CuSO
 
4
· 3H
 
2
O
7.CB.15Aplowite
(Co,Mn,Ni)SO
 
4
· 4H
 
2
O
7.CB.15Boyleite
(Zn,Mg)SO
 
4
· 4H
 
2
O
7.CB.15Ilesite
(Mn,Zn,Fe)SO
 
4
· 4H
 
2
O
7.CB.15Rozenite
FeSO
 
4
· 4H
 
2
O
7.CB.15Starkeyite
MgSO
 
4
· 4H
 
2
O
7.CB.15Drobecite
CdSO
 
4
· 4H
 
2
O
7.CB.15Cranswickite
MgSO
 
4
· 4H
 
2
O
7.CB.20Chalcanthite
CuSO
 
4
· 5H
 
2
O
7.CB.20Jôkokuite
MnSO
 
4
· 5H
 
2
O
7.CB.20Pentahydrite
MgSO
 
4
· 5H
 
2
O
7.CB.20Siderotil
FeSO
 
4
· 5H
 
2
O
7.CB.25Bianchite
(Zn,Fe)SO
 
4
· 6H
 
2
O
7.CB.25Chvaleticeite
(Mn,Mg)SO
 
4
· 6H
 
2
O
7.CB.25Ferrohexahydrite
FeSO
 
4
· 6H
 
2
O
7.CB.25Hexahydrite
MgSO
 
4
· 6H
 
2
O
7.CB.25Moorhouseite
(Co,Ni,Mn)SO
 
4
· 6H
 
2
O
7.CB.25Nickelhexahydrite
(Ni,Mg,Fe)SO
 
4
· 6H
 
2
O
7.CB.30Retgersite
NiSO
 
4
· 6H
 
2
O
7.CB.35Bieberite
CoSO
 
4
· 7H
 
2
O
7.CB.35Boothite
CuSO
 
4
· 7H
 
2
O
7.CB.35Mallardite
MnSO
 
4
· 7H
 
2
O
7.CB.35Melanterite
FeSO
 
4
· 7H
 
2
O
7.CB.35Zincmelanterite
(Zn,Cu,Fe)SO
 
4
· 7H
 
2
O
7.CB.35Alpersite
(Mg,Cu)[SO
 
4
] · 7H
 
2
O
7.CB.40Epsomite
MgSO
 
4
· 7H
 
2
O
7.CB.40Goslarite
ZnSO
 
4
· 7H
 
2
O
7.CB.40Morenosite
NiSO
 
4
· 7H
 
2
O
7.CB.45Alunogen
Al
 
2
(SO
 
4
)
 
3
· 17H
 
2
O
7.CB.45Meta-alunogen
Al
 
2
(SO
 
4
)
 
3
· 12H
 
2
O
7.CB.50Aluminocoquimbite
FeAl(SO
 
4
)
 
3
· 9H
 
2
O
7.CB.55Coquimbite
Fe
 
2-x
Al
 
x
(SO
 
4
)
 
3
· 9H
 
2
O, x ~0.5
7.CB.55Paracoquimbite
Fe
 
2
(SO
 
4
)
 
3
· 9H
 
2
O
7.CB.55Rhomboclase
(H
 
5
O
 
2
)Fe
3+
 
(SO
 
4
)
 
2
· 2H
 
2
O
7.CB.60Kornelite
Fe
 
2
(SO
 
4
)
 
3
· 7H
 
2
O
7.CB.65Quenstedtite
Fe
 
2
(SO
 
4
)
 
3
· 10H
 
2
O
7.CB.70Lausenite
Fe
 
2
(SO
 
4
)
 
3
·6H
 
2
O
7.CB.75Lishizhenite
ZnFe
 
2
(SO
 
4
)
 
4
· 14H
 
2
O
7.CB.75Römerite
Fe
2+
 
Fe
3+
2
(SO
 
4
)
 
4
· 14H
 
2
O
7.CB.80Ransomite
CuFe
 
2
(SO
 
4
)
 
4
· 6H
 
2
O
7.CB.85Apjohnite
Mn
2+
 
Al
 
2
(SO
 
4
)
 
4
· 22H
 
2
O
7.CB.85Bílinite
Fe
2+
 
Fe
3+
2
(SO
 
4
)
 
4
· 22H
 
2
O
7.CB.85Dietrichite
(Zn,Fe
2+
 
,Mn
2+
 
)Al
 
2
(SO
 
4
)
 
4
· 22H
 
2
O
7.CB.85Halotrichite
FeAl
 
2
(SO
 
4
)
 
4
· 22H
 
2
O
7.CB.85Redingtonite
(Fe
2+
 
,Mg,Ni)(Cr,Al)
 
2
(SO
 
4
)
 
4
·22H
 
2
O
7.CB.85Wupatkiite
(Co,Mg,Ni)Al
 
2
(SO
 
4
)
 
4
·22H
 
2
O
7.CB.90Meridianiite
MgSO
 
4
· 11H
 
2
O
Related Minerals - Hey's Index Grouping:

- +
25.3.1Kieserite
MgSO
 
4
· H
 
2
O
25.3.2Sanderite
MgSO
 
4
· 2H
 
2
O
25.3.3Starkeyite
MgSO
 
4
· 4H
 
2
O
25.3.4Pentahydrite
MgSO
 
4
· 5H
 
2
O
25.3.5Hexahydrite
MgSO
 
4
· 6H
 
2
O
25.3.6Epsomite
MgSO
 
4
· 7H
 
2
O
25.3.7Caminite
Mg
 
7
(SO
 
4
)
 
5
(OH)
 
4
· H
 
2
O
25.3.8Vanthoffite
Na
 
6
Mg(SO
 
4
)
 
4
25.3.9Blödite
Na
 
2
Mg(SO
 
4
)
 
2
· 4H
 
2
O
25.3.10Konyaite
Na
 
2
Mg(SO
 
4
)
 
2
· 5H
 
2
O
25.3.11Löweite
Na
 
12
Mg
 
7
(SO
 
4
)
 
13
· 15H
 
2
O
25.3.12Uklonskovite
NaMg(SO
 
4
)F · 2H
 
2
O
25.3.13Langbeinite
K
 
2
Mg
 
2
(SO
 
4
)
 
3
25.3.14Leonite
K
 
2
Mg(SO
 
4
)
 
2
· 4H
 
2
O
25.3.15Picromerite
K
 
2
Mg(SO
 
4
)
 
2
· 6H
 
2
O
25.3.16Efremovite
(NH
 
4
)
 
2
Mg
 
2
(SO
 
4
)
 
3
25.3.17Boussingaultite
(NH
 
4
)
 
2
Mg(SO
 
4
)
 
2
· 6H
 
2
O

Other Names for Pickeringite

Synonyms:
Magnesia AlumMagnesium-HalotrichitePicralluminitePikroalumogenSonomaite
Other Languages:
German:Dumreicherit
Magnesia-Alaun
Pickeringit
Seelandit
Sesqui-Magnesia-alaun
Talkerde-Alaun
Italian:Picroallumogene
Russian:Пиккерингит
Simplified Chinese:镁明矾
Spanish:Pickeringita
Seelandita
Traditional Chinese:鎂明礬
Varieties:
FerropickeringiteKaspariteManganoan Pickeringite

Other Information

Health Warning: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:

- +
Hayes (1844) American Journal of Science: 46: 360.

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 (1942) Academy of Science Philadelphia, Not. Nat. no. 101

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.

European Journal of Mineralogy: 12: 1131-1138.

Internet Links for Pickeringite

Search Engines:
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  • External Links:
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  • Look for Pickeringite on Wikipedia
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  • Raman and XRD data at RRUFF project
  • American Mineralogist Crystal Structure Database
  • Pickeringite details from Handbook of Mineralogy (PDF)
  • Mineral Dealers:
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    Localities for Pickeringite

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