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Tongbaite
A valid IMA mineral species
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Formula:
Cr3C2
Colour:
Brownish yellow
Lustre:
Metallic
Hardness:
8½
Specific Gravity:
6.64 (Calculated)
Crystal System:
Orthorhombic
Name:
Named after its discovery locality, Liu village, Tongbai, Henan Province, China.
Type Locality:
Unique Identifiers
Mindat ID:
3994
Long-form identifier:
mindat:1:1:3994:5
IMA Classification of Tongbaite
Approved
Approval year:
1982
First published:
1983
Classification of Tongbaite
1.BA.15
1 : ELEMENTS (Metals and intermetallic alloys; metalloids and nonmetals; carbides, silicides, nitrides, phosphides)
B : Metallic Carbides, Silicides, Nitrides, Phosphides and Hydrides
A : Carbides
1 : ELEMENTS (Metals and intermetallic alloys; metalloids and nonmetals; carbides, silicides, nitrides, phosphides)
B : Metallic Carbides, Silicides, Nitrides, Phosphides and Hydrides
A : Carbides
Dana 7th ed.:
1.1.26.1
1.1.17.1
1 : NATIVE ELEMENTS AND ALLOYS
1 : Metals, other than the Platinum Group
1 : NATIVE ELEMENTS AND ALLOYS
1 : Metals, other than the Platinum Group
2.4
2 : Carbides, Nitrides, Silicides and Phosphides
2 : Carbides, Nitrides, Silicides and Phosphides
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 for Standard |
|---|---|---|
| Tgb | 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 Tongbaite
Metallic
Transparency:
Opaque
Colour:
Brownish yellow
Streak:
Dark gray
Hardness:
8½ on Mohs scale
Hardness:
VHN100=1885 kg/mm2 - Vickers
Tenacity:
Brittle
Density:
6.64 g/cm3 (Calculated)
Optical Data of Tongbaite
Type:
Biaxial
Anisotropism:
Strong; purplish yellow to yellow-orange.
Bireflectance:
Distinct
Reflectivity:
| Wavelength | R1 (%) | R2 (%) |
|---|---|---|
| 405nm | 46.54% | 49.10% |
| 436nm | 48.50% | 51.28% |
| 480nm | 51.14% | 53.86% |
| 526nm | 53.72% | 55.94% |
| 546nm | 54.68% | 56.89% |
| 578nm | 57.07% | 57.51% |
| 589nm | 57.38% | 57.82% |
| 622nm | 58.72% | 57.68% |
| 644nm | 60.33% | 59.02% |
| 656nm | 61.50% | 59.97% |
| 664nm | 61.56% | 59.97% |
| 700nm | 61.35% | 59.20% |
Graph shows reflectance levels at different wavelengths (in nm). Peak reflectance is 61.56%.
R1 shown in black, R2 shown in red
Colour in reflected light:
Pale violet
Pleochroism:
Visible
Chemistry of Tongbaite
Mindat Formula:
Cr3C2
Elements listed:
Crystallography of Tongbaite
Crystal System:
Orthorhombic
Class (H-M):
mmm(2/m2/m2/m) - Dipyramidal
Space Group:
Pnma
Setting:
Pnma
Cell Parameters:
a = 5.57(5) Å, b = 11.47(8) Å, c = 2.816(8) Å
Ratio:
a:b:c = 0.486 : 1 : 0.246
Unit Cell V:
179.91 ų (Calculated from Unit Cell)
Z:
4
Crystal Structure
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Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
Unit Cell | Unit Cell Packed
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) |
|---|---|---|---|---|---|---|---|
| 0011914 | Tongbaite | Rundqvist S, Runnsjo G (1969) Crystal structure refinement of Cr3C2 Acta Chemica Scandinavica 23 1191-1199 | 1969 | synthetic | 0 | 293 | |
| 0011913 | Tongbaite | Rundqvist S, Runnsjo G (1969) Crystal structure refinement of Cr3C2 Acta Chemica Scandinavica 23 1191-1199 | 1969 | synthetic | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 2.30 Å | (100) |
| 2.23 Å | (80) |
| 1.193 Å | (70) |
| 1.70 Å | (40) |
| 1.164 Å | (40) |
| 1.94 Å | (30) |
| 1.86 Å | (30) |
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 3a: Earth’s earliest Hadean crust | >4.50 |
| 7 : Ultramafic igneous rocks |
Type Occurrence of Tongbaite
General Appearance of Type Material:
Prismatic, pseudohexagonal crystals, to 0.3 mm.
Place of Conservation of Type Material:
National Museum for Geology, Beijing, China, M09332 (type).
Geological Setting of Type Material:
Ultramafic rocks
Associated Minerals at Type Locality:
Synonyms of Tongbaite
Other Language Names for Tongbaite
Related Minerals - Strunz-mindat Grouping
| 1.BA.05 | Cohenite | Fe3C |
| 1.BA.10 | Haxonite | NiFe22C6 |
| 1.BA.10 | Isovite | (Cr,Fe)23C6 |
| 1.BA.20 | Niobocarbide | (Nb,Ta)C |
| 1.BA.20 | Khamrabaevite | (Ti,V,Fe)C |
| 1.BA.20 | Tantalcarbide | TaC |
| 1.BA.25 | Qusongite | WC |
| 1.BA.25 | Zoyashlyukovaite | MoC |
| 1.BA.30 | Yarlongite | Cr4Fe4NiC4 |
| 1.BA.35 | Edscottite | Fe5C2 |
Other Information
Magnetism:
Non-Magnetic
Notes:
Not soluble in HCl, H2SO4 or HNO3. It is weakly attacked by aqua regia.
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 Tongbaite
mindat.org URL:
https://www.mindat.org/min-3994.html
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