Comancheite
A valid IMA mineral species
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About Comancheite
Flag of the Comanche Nation
Formula:
Hg2+55N3-24(NH2,OH)4(Cl,Br)34
Originally assumed to be Hg2+13(Cl,Br)8O9.
Formula revised (IMA 13-B).
Formula revised (IMA 13-B).
Colour:
Red (masses), orange-red to yellow (crystals)
Lustre:
Vitreous, Resinous
Hardness:
2
Specific Gravity:
7.7
Crystal System:
Orthorhombic
Name:
Named in honor of the Comanche, a Native American nation and "the first miners in the Terlingua district...who used cinnabar for warpaint."
Type Locality:
Loosely chemically related to gaildunningite.
The only currently recognized amide mineral. More specifically it is both a nitride and an amide.
The only currently recognized amide mineral. More specifically it is both a nitride and an amide.
Unique Identifiers
Mindat ID:
1114
Long-form identifier:
mindat:1:1:1114:9
IMA Classification of Comancheite
Approved
IMA status notes:
Redefined by the IMA
First published:
1981
Approval history:
Redefined by IMA: 2013
Classification of Comancheite
3.DD.65
3 : HALIDES
D : Oxyhalides, hydroxyhalides and related double halides
D : With Hg
3 : HALIDES
D : Oxyhalides, hydroxyhalides and related double halides
D : With Hg
10.5.5.1
10 : OXYHALIDES AND HYDROXYHALIDES
5 : Am(O,OH)pXq
10 : OXYHALIDES AND HYDROXYHALIDES
5 : Am(O,OH)pXq
8.5.8
8 : Halides - Fluorides, Chlorides, Bromides and Iodides; also Fluoborates and Fluosilicates
5 : Halides of Zn and Hg
8 : Halides - Fluorides, Chlorides, Bromides and Iodides; also Fluoborates and Fluosilicates
5 : Halides of Zn and Hg
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 |
|---|---|---|
| Cmc | 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 Comancheite
Vitreous, Resinous
Transparency:
Transparent, Translucent
Colour:
Red (masses), orange-red to yellow (crystals)
Streak:
Orange-yellow
Hardness:
2 on Mohs scale
Tenacity:
Brittle
Cleavage:
Imperfect/Fair
Parallel to {001} and {110}
Parallel to {001} and {110}
Density:
7.7(4) g/cm3 (Measured) 8.0 g/cm3 (Calculated)
Optical Data of Comancheite
Type:
Biaxial
RI values:
nα = 1.78 nγ = 1.79
Max. Birefringence:
δ = 0.010
Based on recorded range of RI values above.
Based on recorded range of RI values above.
Interference Colours:
The colours simulate birefringence patterns seen in thin section under crossed polars. They do not take into account mineral colouration or opacity.
Michel-Levy Bar The default colours simulate the birefringence range for a 30 µm thin-section thickness. Adjust the slider to simulate a different thickness.
Grain Simulation You can rotate the grain simulation to show how this range might look as you rotated a sample under crossed polars.
The colours simulate birefringence patterns seen in thin section under crossed polars. They do not take into account mineral colouration or opacity.
Michel-Levy Bar The default colours simulate the birefringence range for a 30 µm thin-section thickness. Adjust the slider to simulate a different thickness.
Grain Simulation You can rotate the grain simulation to show how this range might look as you rotated a sample under crossed polars.
Surface Relief:
Moderate
Dispersion:
r > v distinct
Optical Extinction:
Parallel extinction, length fast
Chemistry of Comancheite
Mindat Formula:
Hg2+55N3-24(NH2,OH)4(Cl,Br)34
Originally assumed to be Hg2+13(Cl,Br)8O9.
Formula revised (IMA 13-B).
Originally assumed to be Hg2+13(Cl,Br)8O9.
Formula revised (IMA 13-B).
Element Weights:
Crystallography of Comancheite
Crystal System:
Orthorhombic
Cell Parameters:
a = 18.41 Å, b = 21.64 Å, c = 6.67 Å
Ratio:
a:b:c = 0.851 : 1 : 0.308
Unit Cell V:
2,657.28 ų (Calculated from Unit Cell)
Z:
4
Comment:
Point Group: 2/m 2/m 2/m or mm2.; Space Group: P nnm or P nn2. a
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 5.68 Å | (70) |
| 5.42 Å | (60) |
| 2.878 Å | (80) |
| 2.710 Å | (50) |
| 2.669 Å | (100) |
| 2.457 Å | (50) |
| 1.415 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] | |
| 47g : [Halogen-bearing surface weathering minerals] | |
| Stage 10a: Neoproterozoic oxygenation/terrestrial biosphere | <0.6 |
| 53 : Other minerals with taphonomic origins | <0.4 |
Type Occurrence of Comancheite
General Appearance of Type Material:
Anhedral crystalline masses and as stellate groups of acicular crystals.
Place of Conservation of Type Material:
National Mineral Collection. Geological Survey of Canada, Ottawa, Canada, number GSC 14608.
National Museum of Natural History (Smithsonian Institution), Washington, D.C., USA, number NMNH 150760.
National Museum of Natural History (Smithsonian Institution), Washington, D.C., USA, number NMNH 150760.
Associated Minerals at Type Locality:
Synonyms of Comancheite
Other Language Names for Comancheite
Common Associates
Associated Minerals Based on Photo Data:
Related Minerals - Strunz-mindat Grouping
| 3.DD. | Mikecoxite | [CHg4]OCl2 |
| 3.DD.05 | Eglestonite | [Hg2]2+3OCl3(OH) |
| 3.DD.05 | Kadyrelite | [Hg2]2+3OBr3(OH) |
| 3.DD.10 | Poyarkovite | [Hg2]2+3Cl2O2 |
| 3.DD.15 | Hanawaltite | [Hg2]2+3Hg2+(Cl,OH)2O3 |
| 3.DD.20 | Terlinguaite | [Hg3]4+Hg2+Cl2O2 |
| 3.DD.25 | Pinchite | Hg2+5Cl2O4 |
| 3.DD.30 | Gianellaite | [(Hg2N)2](SO4)(H2O)x |
| 3.DD.30 | Mosesite | (Hg2N)(Cl,SO4,MoO4) · H2O |
| 3.DD.35 | Kleinite | (Hg2N)(Cl,SO4) · nH2O |
| 3.DD.40 | Tedhadleyite | [Hg2]2+5Hg2+I2(Cl,Br)2O4 |
| 3.DD.45 | Vasilyevite | [Hg2]2+10I3Br2Cl[CO3]O6 |
| 3.DD.50 | Aurivilliusite | [Hg2]2+Hg2+2(I,Br,Cl)2O2 |
| 3.DD.55 | Terlinguacreekite | Hg2+3Cl2O2 |
| 3.DD.60 | Kelyanite | [Hg]2+6Sb3+BrCl2O6 |
| 3.DD.70 | Gaildunningite | Hg2+3[NHg2+2]18(Cl,I,OH,Br,S)24 |
Fluorescence of Comancheite
Does not fluoresce
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 Comancheite
mindat.org URL:
https://www.mindat.org/min-1114.html
Please feel free to link to this page.
Please feel free to link to this page.
Search Engines:
External Links:
References for Comancheite
Reference List:
Roberts, A. C., Ansell, H. G., Dunn, P. J. (1981) Comancheite, a new mercury oxychloride-bromide from Terlingua, Texas. The Canadian Mineralogist, 19 (3) 393-396
Cooper, M. A.; Abdu, Y. A.; Hawthorne, F. C.; Kampf, A. R. (2013) The crystal structure of comancheite, Hg2+55N3–24 (OH,NH2)4(Cl,Br)34, and crystal-chemical and spectroscopic discrimination of N3– and O2– anions in Hg2+ compounds. Mineralogical Magazine, 77 (8). 3217-3237 doi:10.1180/minmag.2013.077.8.13
Localities for Comancheite
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.
Germany | |
| Wittern (2001) |
USA | |
| Charles Creekmur collection |
| Roberts et al. (1981) |
| Origlieri (1990) |
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Terlingua Mining District, Texas, USA