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Barwoodite

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About BarwooditeHide

Photo of an old mineral collector
Formula:
Mn2+6Nb5+(SiO4)2O3(OH)3
Colour:
brownish red
Lustre:
Vitreous
Hardness:
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.
Isostructural with:
This page provides mineralogical data about Barwoodite.


Classification of BarwooditeHide

Approved
Approval Year:
2017
First Published:
2018

Physical Properties of BarwooditeHide

Vitreous
Transparency:
Transparent
Colour:
brownish red
Streak:
light orange
Hardness:
3½ on Mohs scale
Tenacity:
Brittle
Cleavage:
Perfect
on {001}
Fracture:
Sub-Conchoidal
Density:
4.1 - 4.4 g/cm3 (Measured)    4.227 g/cm3 (Calculated)

Optical Data of BarwooditeHide

Type:
Uniaxial
RI values:
nω = 1.873() nε = 1.855(5)
Max Birefringence:
δ = 0.018
Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
Surface Relief:
Very High

Chemical Properties of BarwooditeHide

Formula:
Mn2+6Nb5+(SiO4)2O3(OH)3

Crystallography of BarwooditeHide

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 DiffractionHide

Powder Diffraction Data:
d-spacingIntensity
3.994(34)
3.125(95)
2.858(56)
2.688(57)
2.349(81)
1.793(100)
1.669(23)
1.550(75)

Occurrences of BarwooditeHide

Paragenetic Mode(s):

Type Occurrence of BarwooditeHide

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+0.110.772(SiO4)2[O3.58(OH)2.426
Associated Minerals at Type Locality:
Reference:
Kampf, A.R., Celestian, A.J., Nash, B.P. (2018): Barwoodite, Mn6+(Nb5+,⃞)2(SiO4)2(O,OH)6, a New Member of the Welinite Group from Granite Mountain, Arkansas. Canadian Mineralogist, 56, 799-809.

Synonyms of BarwooditeHide

Other Language Names for BarwooditeHide

Afrikaans:Barwoodite

Relationship of Barwoodite to other SpeciesHide

Member of:
Other Members of this group:
FranciscaniteMn2+6(V5+,☐)2(SiO4)2(O,OH)6Hex.
ÖrebroiteMn2+3(Sb5+,Fe3+)(SiO4)(O,OH)3Hex.
WeliniteMn2+6(W6+,Mg)2(SiO4)2(O,OH)6Trig. 3 : P3

Other InformationHide

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.

References for BarwooditeHide

Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Kampf, A.R., Celestian, A.J. and Nash, B.P. (2017) Barwoodite, IMA 2017-046. CNMNC Newsletter No. 39, October 2017, page 1281; Mineralogical Magazine: 81: 1279–1286.
Kampf, A.R., Celestian, A.J., Nash, B.P. (2018): Barwoodite, Mn6+(Nb5+,◻)2(SiO4)2(O,OH)6, a New Member of the Welinite Group from Granite Mountain, Arkansas. Canadian Mineralogist, 56, 799-809.

Internet Links for BarwooditeHide

Localities for BarwooditeHide

This map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.

Locality ListHide

- This locality has map coordinates listed. - This locality has estimated coordinates. ⓘ - Click for 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). Struck out - Mineral was erroneously reported from this locality. Faded * - Never found at this locality but inferred to have existed at some point in the past (eg from pseudomorphs.)

All localities listed without proper references should be considered as questionable.
USA (TL)
 
  • Arkansas
    • Pulaski Co.
      • Little Rock
        • Granite Mountain area
Kampf, A.R., Celestian, A.J. and Nash, B.P. (2017) Barwoodite, IMA 2017-046. CNMNC Newsletter No. 39, October 2017, page 1281; Mineralogical Magazine: 81: 1279–1286; Kampf, A.R., Celestian, A.J., Nash, B.P. (2018): Barwoodite, Mn6+(Nb5+,◻)2(SiO4)2(O,OH)6, a New Member of the Welinite Group from Granite Mountain, Arkansas. Canadian Mineralogist, 56, 799-809.
Steve Stuart collection- collected by Jim Stoops in July 2017. Found by Steve Stuart in material Jim pit on the giveaway tables at the SE Mineralogists Winter Gathering on Feb 2018. Analyzed with EDS by KGD Minerals, Ottawa, Ontario.
Mineral and/or Locality  
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