Ahlfeldite
A valid IMA mineral species - grandfathered
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About Ahlfeldite
Friedrich Ahlfeld
Formula:
Ni(SeO3) · 2H2O
May contain minor Co.
Colour:
apple-green, brown, pink, yellowish
Lustre:
Vitreous
Hardness:
2 - 2½
Specific Gravity:
3.37
Crystal System:
Monoclinic
Name:
Named in honor of Friedrich Ahlfeld ( 6 October 1892, Marburg, German Empire - 9 January 1982, Cochabamba, Bolivia), German-Bolivian mining engineer and geologist, known as the "Father of Bolivian Geology." He built several important collections of Bolivian minerals.
This page provides mineralogical data about Ahlfeldite.
Unique Identifiers
IMA Classification of Ahlfeldite
Approved, 'Grandfathered' (first described prior to 1959)
Classification of Ahlfeldite
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
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 ed.:
34.2.3.3
34.2.3.3
34 : SELENITES, TELLURITES AND SULFITES
2 : A(XO3)·xH2O
34 : SELENITES, TELLURITES AND SULFITES
2 : A(XO3)·xH2O
28.1.13
28 : Selenites, Selenates, Tellurites, and Tellurates
1 : Selenites
28 : Selenites, Selenates, Tellurites, and Tellurates
1 : Selenites
Mineral Symbols
As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.
| Symbol | Source | Reference |
|---|---|---|
| Afe | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
Physical Properties of Ahlfeldite
Vitreous
Transparency:
Transparent
Colour:
apple-green, brown, pink, yellowish
Comment:
Becomes more pink with increasing cobalt content.
Streak:
pale green, white
Hardness:
2 - 2½ on Mohs scale
Tenacity:
Brittle
Cleavage:
Imperfect/Fair
Fair on {110}{103}
Fair on {110}{103}
Density:
3.37(2) g/cm3 (Measured) 3.51 g/cm3 (Calculated)
Optical Data of Ahlfeldite
Type:
Biaxial (-)
RI values:
nα = 1.709(1) nβ = 1.752(1) nγ = 1.787(2)
2V:
Measured: 85° , Calculated: 82°
Max Birefringence:
δ = 0.078
Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
and does not take into account mineral colouration.
Surface Relief:
High
Dispersion:
r < v strong
Optical Extinction:
Y = b; Z ∧ c = –16°.
Pleochroism:
Visible
Comments:
X = pale green; Y = pale pink; Z = pink.
Chemistry of Ahlfeldite
Mindat Formula:
Ni(SeO3) · 2H2O
May contain minor Co.
May contain minor Co.
Elements listed:
Common Impurities:
Co
Crystallography of Ahlfeldite
Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Cell Parameters:
a = 7.53 Å, b = 8.76 Å, c = 6.43 Å
β = 99.08°
β = 99.08°
Ratio:
a:b:c = 0.86 : 1 : 0.734
Unit Cell V:
418.83 ų (Calculated from Unit Cell)
Z:
4
Morphology:
Rare crystals to 1mm, crusts, spherical aggregates
Comment:
Space Group: P21/n.
Crystal Structure
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Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
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2x2x2 | 3x3x3 | 4x4x4
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Data courtesy of the American Mineralogist Crystal Structure Database. Click on an AMCSD ID to view structure
| ID | Species | Reference | Link | Year | Locality | Pressure (GPa) | Temp (K) |
|---|---|---|---|---|---|---|---|
| 0014382 | Ahlfeldite | Larranaga A, Mesa J L, Pizarro J L, Pena A, Chapman J P, Arriortua M I, Rojo T (2005) Thermal, spectroscopic and magnetic properties of the CoxNi1-x(SeO3)*2H2O (x = 0, 0.4, 1) phases crystal structure of Co0.4Ni0.6(SeO3)*2H2O Materials Research Bulletin 40 781-793 | 2005 | synthetic | 0 | 293 | |
| 0014846 | Ahlfeldite | Wildner M (1990) Crystal structure refinements of synthetic cobaltomenite (CoSeO3*2H2O) and ahlfeldite (NiSeO3*2H2O) Neues Jahrbuch fur Mineralogie, Monatshefte 1990 353-362 | 1990 | synthetic | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 5.69 Å | (100) |
| 3.426 Å | (80) |
| 2.992 Å | (75) |
| 2.190 Å | (75) |
| 3.772 Å | (60) |
| 2.719 Å | (60) |
| 2.354 Å | (50) |
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 7: Great Oxidation Event | <2.4 |
| 47a : [Near-surface hydration of prior minerals] | |
| 47e : [Vanadates, chromates, manganates] |
Geological Setting:
Alteration product of nickel sulfides and selenides
Type Occurrence of Ahlfeldite
General Appearance of Type Material:
Rare crystals, to 1 mm; in crystalline crusts and spherical aggregates.
Place of Conservation of Type Material:
Natural History Museum, London
Geological Setting of Type Material:
alteration product of nickel-bearing selenides and sulfides.
Associated Minerals at Type Locality:
Reference:
Herzenberg, R., Ahlfeld, F. (1935) Blockit, ein neues Selenerz aus Bolivien. Zentralblatt Mineralien, Abteilung A: 6: 277-279.
Other Language Names for Ahlfeldite
Relationship of Ahlfeldite to other Species
Forms a series with:
Common Associates
Associated Minerals Based on Photo Data:
| 14 photos of Ahlfeldite associated with Chalcomenite | CuSeO3 · 2H2O |
| 6 photos of Ahlfeldite associated with Alfredopetrovite | Al2(Se4+O3)3 · 6H2O |
| 2 photos of Ahlfeldite associated with Goethite | α-Fe3+O(OH) |
| 2 photos of Ahlfeldite associated with Krut'aite | CuSe2 |
| 2 photos of Ahlfeldite associated with Molybdomenite | PbSeO3 |
| 2 photos of Ahlfeldite associated with Felsőbányaite | Al4(SO4)(OH)10 · 4H2O |
| 1 photo of Ahlfeldite associated with Anglesite | PbSO4 |
| 1 photo of Ahlfeldite associated with Clinochalcomenite | CuSeO3 · 2H2O |
| 1 photo of Ahlfeldite associated with Cobaltomenite | CoSeO3 · 2H2O |
| 1 photo of Ahlfeldite associated with Selenium | Se |
Related Minerals - Strunz-mindat Grouping
| 4.JH. | Bernardevansite | Al2(SeO3)3 · 6H2O |
| 4.JH.05 | Chalcomenite | CuSeO3 · 2H2O |
| 4.JH.10 | Clinochalcomenite | CuSeO3 · 2H2O |
| 4.JH.10 | Cobaltomenite | CoSeO3 · 2H2O |
| 4.JH.15 | Mandarinoite | Fe3+2(Se4+O3)3 · (6-x)H2O (x = 0.0-1.0) |
| 4.JH.20 | Orlandiite | Pb3(SeO3)(Cl,OH)4 · H2O |
| 4.JH.25 | Larisaite | Na(H3O)(UO2)3(SeO3)O2 · 4H2O |
| 4.JH.30 | Nestolaite | CaSeO3 · H2O |
Other Information
Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.
Internet Links for Ahlfeldite
mindat.org URL:
https://www.mindat.org/min-61.html
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References for Ahlfeldite
Reference List:
Aristarain, L. F., Hurlbut, C. S. Jr. (1969) Ahlfeldite from Pacajake, Bolivia; A restudy. American Mineralogist, 54 (3-4) 448-456
Charykova, M. V., Krivovichev, V. G., Lelet, M. I., Yakovenko, O. S., Suleimanov, E. V., Depmeier, W., Semenova, V. V., Zorina, M. L. (2014) A calorimetric and thermodynamic investigation of the synthetic analogs of cobaltomenite, CoSeO3·2H2O, and ahlfeldite, NiSeO3·2H2O. American Mineralogist, 99 (4) 742-748 doi:10.2138/am.2014.4588
Localities for Ahlfeldite
symbol to view information about a locality.
The Locality List
- This locality has map coordinates listed.
- This locality has estimated coordinates.
ⓘ - Click for references and further information on this occurrence.
? - Indicates mineral may be doubtful at this locality.
- Good crystals or important locality for species.
- World class for species or very significant.
(TL) - Type Locality for a valid mineral species.
(FRL) - First Recorded Locality for everything else (eg varieties).
All localities listed without proper references should be considered as questionable.
Bolivia | |
| doi:10.3390/min7050068 +3 other references |
| Herzenberg (1935) +3 other references |
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El Dragón mine, Porco Municipality, Antonio Quijarro Province, Potosí, Bolivia