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Ahlfeldite

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El Dragón mine, Antonio Quijarro Province, Potosí Department, Bolivia
© Brent Thorne

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Formula:
(Ni,Co)[SeO
 
3
] · 2H
 
2
O
System:MonoclinicColour:apple-green, brown, ...
Lustre:VitreousHardness:2 - 2½
Name:Named after Friedrich Ahlfed (1892-1982), German-Bolivian mining engineer and geologist.
This page provides mineralogical data about Ahlfeldite.

Classification of Ahlfeldite

IMA status:Valid - first described prior to 1959 (pre-IMA) - "Grandfathered"
Strunz 8th edition ID:4/K.07-30
Nickel-Strunz 10th (pending) edition ID:4.JH.10

4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
J : Arsenites, antimonites, bismuthites, sulfites, selenites, tellurites; iodates
H : Selenites without additional anions, with H2O
Dana 7th edition ID:34.2.3.3
Dana 8th edition ID:34.2.3.3

34 : SELENITES, TELLURITES AND SULFITES
2 : A(XO3)·xH2O
Hey's CIM Ref.:28.1.13

28 : Selenites, Selenates, Tellurites, and Tellurates
1 : Selenites
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Type Occurrence of Ahlfeldite

Type Locality:Virgen de Surumi mine (Pacajake mine; Pakajake mine), Pakajake Canyon (Pacajake Canyon), Chayanta Province, Potosí Department, Bolivia
Place of Conservation of Type Material:Natural History Museum, London
Year of Discovery:1935

Occurrences of Ahlfeldite

Geological Setting:Alteration product of nickel sulfides and selenides

Physical Properties of Ahlfeldite

Lustre:Vitreous
Diaphaneity (Transparency):Transparent
Colour:apple-green, brown, pink, yellowish
Comment:Becomes more pink with increasing cobalt content.
Streak:pale green, white
Hardness (Mohs):2 - 2½
Tenacity:Brittle
Cleavage:Imperfect/Fair
Fair on {110}{103}
Density (measured):3.37(2) g/cm3
Density (calculated):3.51 g/cm3

Crystallography of Ahlfeldite

Crystal System:Monoclinic
Class (H-M):2/m - Prismatic
Cell Parameters:a = 7.53Å, b = 8.76Å, c = 6.43Å
β = 99.08°
Ratio:a:b:c = 0.86 : 1 : 0.734
Unit Cell Volume:V 418.83 ų (Calculated from Unit Cell)
Z:4
Morphology:Rare crystals to 1mm, crusts, spherical aggregates

Optical Data of Ahlfeldite

Type:Biaxial (-)
RI values: nα = 1.709 nβ = 1.752 nγ = 1.787
2V:Measured: 85° , Calculated: 82°
Maximum Birefringence:δ = 0.078

Chart shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
Surface Relief:High
Dispersion:r < v strong
Pleochroism:Visible
Comments:X = pale green
Y = pale pink
Z = pink

Chemical Properties of Ahlfeldite

Formula:
(Ni,Co)[SeO
 
3
] · 2H
 
2
O
Essential elements:H, Ni, O, Se
All elements listed in formula:Co, H, Ni, O, Se
Common Impurities:Co

Relationship of Ahlfeldite to other Species

Series:Forms a series with Cobaltomenite (see here)
Related Minerals - Nickel-Strunz Grouping):

- +
4.JH.05Chalcomenite
Cu[SeO
 
3
] · 2H
 
2
O
4.JH.10Clinochalcomenite
Cu[SeO
 
3
] · 2H
 
2
O
4.JH.10Cobaltomenite
Co[SeO
 
3
] · 2H
 
2
O
4.JH.15Mandarinoite
Fe
 
2
Se
 
3
O
 
9
·4H
 
2
O
4.JH.20Orlandiite
Pb
 
10
(SeO
 
4
)O
 
7
Cl
 
4
·H
 
2
O
4.JH.20UM1999-29-SeO:ClCuHPb
Pb
 
4
CuCl
 
3
(SeO
 
3
)
 
3
(OH)
4.JH.25Larisaite
Na(H
 
3
O)(UO
 
2
)
 
3
(SeO
 
3
)O
 
2
·4H
 
2
O
Related Minerals - Hey's Index Grouping:

- +
28.1.1Chalcomenite
Cu[SeO
 
3
] · 2H
 
2
O
28.1.2Clinochalcomenite
Cu[SeO
 
3
] · 2H
 
2
O
28.1.3Francisite
Cu
 
3
Bi(SeO
 
3
)
 
2
O
 
2
Cl
28.1.4Sophiite
Zn
 
2
[Cl
 
2
|SeO
 
3
]
28.1.5Molybdomenite
PbSeO
 
3
28.1.6Haynesite
(UO
 
2
)
 
3
(OH)
 
2
(SeO
 
3
)
 
2
·5H
 
2
O
28.1.7Derriksite
Cu
 
4
UO
 
2
(SeO
 
3
)
 
2
(OH)
 
6
·H
 
2
O
28.1.8Marthozite
Cu(UO
 
2
)
 
3
(SeO
 
3
)
 
3
(OH)
 
2
·7H
 
2
O
28.1.9Guilleminite
Ba(UO
 
2
)
 
3
(SeO
 
3
)
 
2
(OH)
 
4
·3H
 
2
O
28.1.10Demesmaekerite
Pb
 
2
Cu
 
5
(UO
 
2
)
 
2
(SeO
 
3
)
 
6
(OH)
 
6
·2H
 
2
O
28.1.11Mandarinoite
Fe
 
2
Se
 
3
O
 
9
·4H
 
2
O
28.1.12Cobaltomenite
Co[SeO
 
3
] · 2H
 
2
O
Related Minerals - Dana Grouping):

- +
34.2.3.1Clinochalcomenite
Cu[SeO
 
3
] · 2H
 
2
O
34.2.3.2Cobaltomenite
Co[SeO
 
3
] · 2H
 
2
O

Other Names for Ahlfeldite

Other Languages:
German:Ahlfeldit
Italian:Ahlfeldite
Russian:Альфильдит
Spanish:Ahlfeldita

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 Ahlfeldite

Reference List:Herzenberg (1935) Zentralblatt Mineralien, Abteil A (1935), 6, 189 and 279.

Herzenberg (1945) Inst. Boliviano de Ing. De Minas y Geol., Publ. Técu, La Paz, no. 5.

Herzenberg (1945) Mineria Boliviana: 2: no. 25.

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.: 635.

American Mineralogist (1963): 48: 1183.

Canadian Mineralogist (1974): 12: 304-307.

Neues Jahrbuch für Mineralogie, Monatshefte (1990): 353-362.

Boletín Facultad de cienncias exactus, físicas y naturals, Universidad nacional de Córdoba: 7: 1-4.

Internet Links for Ahlfeldite

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  • Raman and XRD data at RRUFF project
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    Localities for Ahlfeldite

    (TL) indicates type locality. ? indicates mineral may be doubtful at this locality. All other localities listed without reference should be considered as uncertain and unproven until references can be found.
    Bolivia
     
    • Potosí Department
      • Antonio Quijarro Province
    		[MinRec 21:133]
      • Chayanta Province
        • Pakajake Canyon (Pacajake Canyon)
    		Herzenberg (1935) Zentralbl. Min., Abt. A: 189 & 279; 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: 635; Mineralogical Record 32: 476.; Amer.Min.(1969) 54, 1519-1527
    Mineral and/or Locality
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