Molybdofornacite
A valid IMA mineral species
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About Molybdofornacite
Formula:
Pb2Cu(MoO4,CrO4)(AsO4,PO4)(OH)
Colour:
Light green, olive green
Lustre:
Adamantine, Sub-Adamantine, Vitreous, Resinous, Greasy
Hardness:
3 - 4
Specific Gravity:
6.57
Crystal System:
Monoclinic
Name:
Named for its relationship to fornacite, but with molybdenum dominant over chromium.
Isostructural with:
Unique Identifiers
Mindat ID:
2734
Long-form identifier:
mindat:1:1:2734:8
GUID
(UUID V4):
(UUID V4):
a249325f-3d6e-4d28-a925-4d7dbdc80629
IMA Classification of Molybdofornacite
Approved
IMA Formula:
CuPb2(MoO4)(AsO4)(OH)
Approval year:
1982
First published:
1983
Classification of Molybdofornacite
7.FC.10
7 : SULFATES (selenates, tellurates, chromates, molybdates, wolframates)
F : Chromates
C : With PO4, AsO4, SiO4
7 : SULFATES (selenates, tellurates, chromates, molybdates, wolframates)
F : Chromates
C : With PO4, AsO4, SiO4
43.4.3.3
43 : COMPOUND PHOSPHATES, ETC.
4 : Anhydrous Compound Phosphates, etc·, Containing Hydroxyl or Halogen
43 : COMPOUND PHOSPHATES, ETC.
4 : Anhydrous Compound Phosphates, etc·, Containing Hydroxyl or Halogen
22.5.5
22 : Phosphates, Arsenates or Vanadates with other Anions
5 : Phosphates, arsenates or vanadates with chromate, molybdate, niobate or tantalate
22 : Phosphates, Arsenates or Vanadates with other Anions
5 : Phosphates, arsenates or vanadates with chromate, molybdate, niobate or tantalate
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 |
|---|---|---|
| Mfor | 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 Molybdofornacite
Adamantine, Sub-Adamantine, Vitreous, Resinous, Greasy
Transparency:
Transparent, Translucent
Colour:
Light green, olive green
Streak:
Pale Yellow
Hardness:
3 - 4 on Mohs scale
Tenacity:
Brittle
Cleavage:
None Observed
Fracture:
Conchoidal
Density:
6.57 g/cm3 (Measured) 6.6 g/cm3 (Calculated)
Optical Data of Molybdofornacite
Type:
Biaxial (+)
RI values:
nα = 2.050(2) nγ = 2.150(2)
Birefringence:
0.10
Max Birefringence:
δ = 0.100
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:
Moderate
Dispersion:
r < v strong
Pleochroism:
Strong
Comments:
X and Y pale yellow, Z green yellow.
Chemistry of Molybdofornacite
Mindat Formula:
Pb2Cu(MoO4,CrO4)(AsO4,PO4)(OH)
Crystallography of Molybdofornacite
Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Space Group:
P21/b
Setting:
P21/c
Cell Parameters:
a = 8.100(5) Å, b = 5.946(3) Å, c = 17.651(1) Å
β = 109.17(5)°
β = 109.17(5)°
Ratio:
a:b:c = 1.362 : 1 : 2.969
Unit Cell V:
802.98 ų (Calculated from Unit Cell)
Z:
4
Twinning:
Rare “butterfly” contact twins, at 120 degrees.
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 8.27 Å | (10) |
| 4.84 Å | (50) |
| 4.50 Å | (5) |
| 4.15 Å | (30) |
| 4.06 Å | (20) |
| 3.78 Å | (10) |
| 3.41 Å | (40) |
| 3.32 Å | (100) |
| 3.23 Å | (5) |
| 3.11 Å | (3) |
| 2.979 Å | (60) |
| 2.937 Å | (40) |
| 2.845 Å | (60) |
| 2.753 Å | (60) |
| 2.635 Å | (10) |
| 2.555 Å | (5) |
| 2.460 Å | (5) |
| 2.433 Å | (10) |
| 2.353 Å | (50) |
| 2.149 Å | (3) |
| 2.093 Å | (30) |
| 2.070 Å | (3) |
| 2.006 Å | (30) |
| 1.914 Å | (20) |
| 1.898 Å | (10) |
| 1.864 Å | (20) |
| 1.795 Å | (10) |
| 1.776 Å | (10) |
| 1.670 Å | (30) |
| 1.624 Å | (10) |
Comments:
ICDD 35-593.
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 7: Great Oxidation Event | <2.4 |
| 47a : [Near-surface hydration of prior minerals] | |
| 47d : [Arsenates, antimonates, selenates, bismuthinates] | |
| 47h : [Near-surface oxidized, dehydrated minerals] |
Type Occurrence of Molybdofornacite
General Appearance of Type Material:
Minute lath-like crystals on dioptase
Place of Conservation of Type Material:
Mineralogical Institute, Ruhr-University, Bochum, Germany.
Geological Setting of Type Material:
Oxidation zone
Associated Minerals at Type Locality:
Reference:
Medenbach, O., Abraham, K., Gebert, W. (1983) Molybdofornacit, ein neues Blei-Kupfer-Arsenat-Molybdat-Hydroxid von Tsumeb, Namibia. Neues Jahrbuch für Mineralogie, Monatshefte: 1983: 289-295.
Synonyms of Molybdofornacite
Other Language Names for Molybdofornacite
German:Molybdofornacit
Spanish:Molybdofornacita
Common Associates
Associated Minerals Based on Photo Data:
| 21 photos of Molybdofornacite associated with Wulfenite | Pb(MoO4) |
| 20 photos of Molybdofornacite associated with Malachite | Cu2(CO3)(OH)2 |
| 13 photos of Molybdofornacite associated with Dioptase | CuSiO3 · H2O |
| 10 photos of Molybdofornacite associated with Quartz | SiO2 |
| 4 photos of Molybdofornacite associated with Mimetite | Pb5(AsO4)3Cl |
| 3 photos of Molybdofornacite associated with Chalcocite | Cu2S |
| 2 photos of Molybdofornacite associated with Anglesite | PbSO4 |
| 2 photos of Molybdofornacite associated with Adularia | KAlSi3O8 |
| 2 photos of Molybdofornacite associated with Limonite | |
| 2 photos of Molybdofornacite associated with Hemimorphite | Zn4Si2O7(OH)2 · H2O |
Related Minerals - Strunz-mindat Grouping
| 7.FC.05 | Vauquelinite | Pb2Cu(CrO4)(PO4)(OH) |
| 7.FC.10 | Fornacite | Pb2Cu(CrO4)(AsO4)(OH) |
| 7.FC.15 | Hemihedrite | Pb10Zn(CrO4)6(SiO4)2(OH)2 |
| 7.FC.15 | Iranite | Pb10Cu(CrO4)6(SiO4)2(OH)2 |
| 7.FC.15 | Raygrantite | Pb10Zn(SO4)6(SiO4)2(OH)2 |
| 7.FC.20 | Cassedanneite | Pb5(CrO4)2(VO4)2 · H2O |
| 7.FC.20 | Embreyite | Pb5(CrO4)2(PO4)2 · H2O |
Fluorescence of Molybdofornacite
Not known to fluoresce in UV
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 Molybdofornacite
mindat.org URL:
https://www.mindat.org/min-2734.html
Please feel free to link to this page.
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External Links:
References for Molybdofornacite
Localities for Molybdofornacite
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.
Chile | |
| Maurizio Dini collection |
| Maurizio Dini collection (material analysed by Dr. Jochen Schlüter) +1 other reference |
France | |
| N. Meisser (XRD and SEM-EDS analyses) +1 other reference |
Germany | |
| Collection of Steffen Michalski |
Namibia (TL) | |
| Medenbach et al. (1983) |
Spain | |
| Calvo Rebollar et al. (2022) |
Switzerland | |
| Ansermet (2012) |
USA | |
| Ron Layton self collected |
| Peter Mcgaw |
| Peter Megaw | |
| Anthony et al. (1995) |
| Frost et al. (2007) |
| - (n.d.) |
| Allen et al. (1988) +1 other reference |
| Thorne (n.d.) |
| Collection of John Dagenais |
| Collected by Sugar White. In the ... |
| Dr. William S. Wise presentation to ... |
| Castor et al. (2004) |
| Min Rec 20:1 p57 |
| Walstrom (n.d.) +2 other references |
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Tsumeb Mine, Tsumeb, Oshikoto Region, Namibia