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Ahlfeldite

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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 Ahlfeld (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
CuSeO
 
3
· 2H
 
2
O
4.JH.10Clinochalcomenite
CuSeO
 
3
· 2H
 
2
O
4.JH.10Cobaltomenite
CoSeO
 
3
· 2H
 
2
O
4.JH.15Mandarinoite
Fe
3+
2
(SeO
 
3
)
 
3
· 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
Cu(SeO
 
3
)
 
3
(OH)Cl
 
3
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
CuSeO
 
3
· 2H
 
2
O
28.1.2Clinochalcomenite
CuSeO
 
3
· 2H
 
2
O
28.1.3Francisite
Cu
 
3
Bi(SeO
 
3
)
 
2
O
 
2
Cl
28.1.4Sophiite
Zn
 
2
(SeO
 
3
)Cl
 
2
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
3+
2
(SeO
 
3
)
 
3
· 4H
 
2
O
28.1.12Cobaltomenite
CoSeO
 
3
· 2H
 
2
O
Related Minerals - Dana Grouping):

- +
34.2.3.1Clinochalcomenite
CuSeO
 
3
· 2H
 
2
O
34.2.3.2Cobaltomenite
CoSeO
 
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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  • Localities for Ahlfeldite

    The map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.
    (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
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    Copyright © Jolyon Ralph and Ida Chau 1993-2011. Site Map. Locality, mineral & photograph data are the copyright of the individuals who submitted them.Further information contact the Site hosted & developed by Jolyon Ralph. Mindat.org is an online information resource dedicated to providing free mineralogical information to all. Mindat relies on the contributions of hundreds of members and supporters. Mindat does not offer minerals for sale. If you would like to add information to improve the quality of our database, then click here to register. Current server date and time: 18th Jun 2011 16:23:40
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