Barwoodite
A valid IMA mineral species
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About Barwoodite
Photo of an old mineral collector
Formula:
Mn2+6Nb5+(SiO4)2O3(OH)3
Colour:
Brownish red
Lustre:
Vitreous
Hardness:
3½
Specific Gravity:
4.1 - 4.4
Crystal System:
Trigonal
Member of:
Name:
Named in honor of Henry “Bumpi” L. Barwood (1947, Alameda, California, USA - 2016, Alabama, USA), professor of geology at Troy University, Troy, Alabama, USA. Dr. Barwood was also very active in the mineral collecting community and on MinDat.
Type Locality:
Isostructural with:
This page provides mineralogical data about Barwoodite.
Unique Identifiers
Mindat ID:
52148
Long-form identifier:
mindat:1:1:52148:4
IMA Classification of Barwoodite
Approved
IMA Formula:
Mn2+6(Nb5+,◻)2(SiO4)2(O,OH)6
Approval year:
2017
First published:
2018
Classification of Barwoodite
9.AF.
9 : SILICATES (Germanates)
A : Nesosilicates
F : Nesosilicates with additional anions; cations in [4], [5] and/or only [6] coordination
9 : SILICATES (Germanates)
A : Nesosilicates
F : Nesosilicates with additional anions; cations in [4], [5] and/or only [6] coordination
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 |
|---|---|---|
| Bwo | 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 Barwoodite
Vitreous
Transparency:
Transparent
Colour:
Brownish red
Streak:
Light orange
Hardness:
3½ on Mohs scale
Tenacity:
Brittle
Cleavage:
Perfect
on {001}
on {001}
Fracture:
Sub-Conchoidal
Density:
4.1 - 4.4 g/cm3 (Measured) 4.227 g/cm3 (Calculated)
Optical Data of Barwoodite
Type:
Uniaxial
RI values:
nω = 1.873(3) nε = 1.855(5)
Max. Birefringence:
δ = 0.018
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. Each grain retains its interference colour (retardation) while its brightness falls to black at extinction and reaches a maximum between extinction positions.
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. Each grain retains its interference colour (retardation) while its brightness falls to black at extinction and reaches a maximum between extinction positions.
Surface Relief:
Moderate
Chemistry of Barwoodite
Mindat Formula:
Mn2+6Nb5+(SiO4)2O3(OH)3
Element Weights:
Crystallography of Barwoodite
Crystal System:
Trigonal
Class (H-M):
3 - Pyramidal
Space Group:
P3
Cell Parameters:
a = 8.2139(10) Å, c = 4.8117(4) Å
Ratio:
a:c = 1 : 0.586
Unit Cell V:
281.14 ų
Z:
1
Morphology:
Hexagonal plates
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 3.994 Å | (34) |
| 3.125 Å | (95) |
| 2.858 Å | (56) |
| 2.688 Å | (57) |
| 2.349 Å | (81) |
| 1.793 Å | (100) |
| 1.669 Å | (23) |
| 1.550 Å | (75) |
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 4b: Highly evolved igneous rocks | >3.0 |
| 34 : Complex granite pegmatites |
Type Occurrence of Barwoodite
General Appearance of Type Material:
Brownish-red plates to about 3 mm in diameter and 0.5 mm thick.
Place of Conservation of Type Material:
Cotype material is deposited in the mineralogical collections of the Natural History Museum of Los Angeles County, 900 Exposition Boulevard, Los Angeles, CA 90007, USA, catalogue numbers 66634, 66635, 66636 and 66637.
Empirical Formula of Type Material:
Mn+62(Nb5+0.94Fe3+0.18Mn3+0.11◻ 0.77)Σ2(SiO4)2[O3.58(OH)2.42]Σ6
Associated Minerals at Type Locality:
Synonyms of Barwoodite
Other Language Names for Barwoodite
Relationship of Barwoodite to other Species
Member of:
Other Members of Welinite Group:
| Franciscanite | Mn2+6(V5+,◻)2(SiO4)2(O,OH)6 | Trig. 3 : P3 |
| Örebroite | Mn2+3(Sb5+,Fe3+)(SiO4)(O,OH)3 | Trig. 3 : P3 |
| Scorticoite | Mn6(Sb,◻)Σ2(SiO4)2O3(OH)3 | Trig. 3 : P3 |
| Welinite | Mn2+6(W6+,Mg)2(SiO4)2(O,OH)6 | Trig. 3 : P3 |
Common Associates
Associations Based on Photo Data:
Related Minerals - Strunz-mindat Grouping
| 9.AF. | Chegemite | Ca7(SiO4)3(OH)2 |
| 9.AF. | Jingwenite-(Y) | YAlV4+(SiO4)O2(OH)2 |
| 9.AF.05 | Sillimanite | Al2(SiO4)O |
| 9.AF.05 | 'Xenolite' | Al10Si8O31 |
| 9.AF.10 | Kanonaite | Mn3+Al(SiO4)O |
| 9.AF.10 | Andalusite | Al2(SiO4)O |
| 9.AF.15 | Kyanite | Al2(SiO4)O |
| 9.AF.20 | Krieselite | Al2(GeO4)F2 |
| 9.AF.20 | Mullite | Al4+2xSi2-2xO10-x |
| 9.AF.23 | Boromullite | Al9BSi2O19 |
| 9.AF.25 | Yoderite | Mg(Al,Fe3+)3(SiO4)2O(OH) |
| 9.AF.30 | Zincostaurolite | Zn2Al9Si4O23(OH) |
| 9.AF.30 | Staurolite | Fe2+2Al9Si4O23(OH) |
| 9.AF.30 | Magnesiostaurolite | Mg(Mg,Li)3(Al,Mg)18Si8O44(OH)4 |
| 9.AF.35 | Topaz | Al2(SiO4)(F,OH)2 |
| 9.AF.40 | Norbergite | Mg3(SiO4)F2 |
| 9.AF.45 | Chondrodite | Mg5(SiO4)2F2 |
| 9.AF.45 | Kumtyubeite | Ca5(SiO4)2F2 |
| 9.AF.45 | Reinhardbraunsite | Ca5(SiO4)2(OH,F)2 |
| 9.AF.45 | Hydroxylchondrodite | Mg5(SiO4)2(OH)2 |
| 9.AF.45 | Alleghanyite | Mn2+5(SiO4)2(OH)2 |
| 9.AF.50 | 'Unnamed (Ca-analogue of Humite)' | Ca7(SiO4)4F2 |
| 9.AF.50 | Humite | Mg7(SiO4)3F2 |
| 9.AF.50 | Manganhumite | Mn2+7(SiO4)3(OH)2 |
| 9.AF.50 | 'Unnamed (OH-analogue of humite)' | Mg7(SiO4)3(OH)2 |
| 9.AF.50 | Fluorchegemite | Ca7(SiO4)3F2 |
| 9.AF.55 | Hydroxylclinohumite | Mg9(SiO4)4(OH)2 |
| 9.AF.55 | Clinohumite | Mg9(SiO4)4F2 |
| 9.AF.55 | Sonolite | Mn2+9(SiO4)4(OH)2 |
| 9.AF.60 | Leucophoenicite | Mn2+7(SiO4)3(OH)2 |
| 9.AF.65 | Ribbeite | Mn2+5(SiO4)2(OH)2 |
| 9.AF.70 | Jerrygibbsite | Mn2+9(SiO4)4(OH)2 |
| 9.AF.75 | Franciscanite | Mn2+6(V5+,◻)2(SiO4)2(O,OH)6 |
| 9.AF.75 | Scorticoite | Mn6(Sb,◻)Σ2(SiO4)2O3(OH)3 |
| 9.AF.75 | Welinite | Mn2+6(W6+,Mg)2(SiO4)2(O,OH)6 |
| 9.AF.75 | Örebroite | Mn2+3(Sb5+,Fe3+)(SiO4)(O,OH)3 |
| 9.AF.80 | Ellenbergerite | Mg6(Mg,Ti,Zr,◻)2(Al,Mg)6Si8O28(OH)10 |
| 9.AF.85 | Magnesiochloritoid | MgAl2O(SiO4)(OH)2 |
| 9.AF.85 | Ottrélite | Mn2+Al2O(SiO4)(OH)2 |
| 9.AF.85 | Chloritoid | Fe2+Al2O(SiO4)(OH)2 |
| 9.AF.90 | Olmiite | CaMn2+[SiO3(OH)](OH) |
| 9.AF.90 | Poldervaartite | CaCa[SiO3(OH)](OH) |
| 9.AF.95 | Pilawite-(Y) | Ca2Y2Al4(SiO4)4O2(OH)2 |
Other Information
Notes:
Loses color very slowly in dilute HCl and slowly in concentrated HCl at room temperature, but does not dissolve.
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 Barwoodite
mindat.org URL:
https://www.mindat.org/min-52148.html
Please feel free to link to this page.
Please feel free to link to this page.
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External Links:
Mineral Dealers:
References for Barwoodite
Reference List:
Hålenius, U., Hatert, F., Pasero, M., Mills, S. J. (2017) New minerals and nomenclature modifications approved in 2017, CNMNC Newsletter No 39. Mineralogical Magazine, 81 (5) 1279-1286 doi:10.1180/minmag.2017.081.072
Localities for Barwoodite
Showing 2 localities.
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.
USA (TL) | |
| Hålenius et al. (2017) +2 other references |
| Steve Stuart collection- collected by ... |
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Big Rock Quarry, Granite Mountain area, Little Rock, Pulaski County, Arkansas, USA