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Magnesiobeltrandoite-2N3S

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Formula:
(Mg6Al2)(Al18Fe3+2)O38(OH)2
Colour:
Black
Lustre:
Vitreous
Hardness:
6 - 6½
Specific Gravity:
3.93 (Calculated)
Crystal System:
Trigonal
Isostructural with:
This page provides mineralogical data about Magnesiobeltrandoite-2N3S.


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Classification of Magnesiobeltrandoite-2N3SHide

Approved
Approval Year:
2016
First Published:
2018

Physical Properties of Magnesiobeltrandoite-2N3SHide

Vitreous
Colour:
Black
Comment:
Dark reddish-brown in thin section
Streak:
Dark brown
Hardness:
6 - 6½ on Mohs scale
Comment:
≈6–6½
Tenacity:
Brittle
Cleavage:
None Observed
Fracture:
Irregular/Uneven
Density:
3.93 g/cm3 (Calculated)

Optical Data of Magnesiobeltrandoite-2N3SHide

Type:
Uniaxial (-)
Pleochroism:
Weak
Comments:
With ε = deep reddish brown (along c axis) and ω = reddish brown (⊥ c). Absorption is E > O.
Comments:
An estimated mean refractive index of ca. 1.80.

Chemical Properties of Magnesiobeltrandoite-2N3SHide

Formula:
(Mg6Al2)(Al18Fe3+2)O38(OH)2
IMA Formula:
(Mg6Al2)(Al18Fe3+2)O38(OH)2

Crystallography of Magnesiobeltrandoite-2N3SHide

Crystal System:
Trigonal
Class (H-M):
3m - Ditrigonal Pyramidal
Space Group:
P3m1
Cell Parameters:
a = 5.7226(3) Å, c = 23.0231(9) Å
Ratio:
a:c = 1 : 4.023
Unit Cell V:
652.95 ų (Calculated from Unit Cell)

X-Ray Powder DiffractionHide

Powder Diffraction Data:
d-spacingIntensity
2.858(42)
2.735(51)
2.484(46)
2.427(100)
1.568(29)
1.514(30)
1.438(42)
1.429(72)

Type Occurrence of Magnesiobeltrandoite-2N3SHide

General Appearance of Type Material:
As subhedral to euhedral black crystals (∼50–400μm) in a fine-grained chlorite matrix associated as inclusions to relict pre-Alpine hercynite spinels and dolomite in cm- to dm-long darker boudins, which are cut by corundum + clinochlore ± dolomite veins
Place of Conservation of Type Material:
Mineralogical collections of the Museo Regionale di Scienze Naturali, Sezione di Mineralogia, Petrografia e Geologia, via Giovanni Giolitti 36, I-10123 Torino, Italy (catalogue number M/U17182)
Empirical Formula of Type Material:
[Al18.36Mg3.96Fe2+2:52Fe3+2:08Ti0.56Cr0.40Zn0.06V3+0:03Mn0.0228O38(OH)2
Geological Setting of Type Material:
Magnesian chloritites of a metamorphosed layered mafic complex
Associated Minerals at Type Locality:
Reference:
Cámara, F., Cossio, R., Regis, D., Cerantola, V., Ciriotti, M.E., Compagnoni, R. (2018): Beltrandoite, a new root-name in the högbomite supergroup: the Mg end-member magnesiobeltrandoite-2N3S. European Journal of Mineralogy, 30: 545-558

Synonyms of Magnesiobeltrandoite-2N3SHide

Relationship of Magnesiobeltrandoite-2N3S to other SpeciesHide

Other Members of this group:
Högbomite Group
Nigerite Group
Taaffeite Group
Zincovelesite-6N6SZn3(Fe3+,Mn3+,Al,Ti)8O15(OH)Trig. 3m (3 2/m) : P3m1

Fluorescence of Magnesiobeltrandoite-2N3SHide

No fluorescence under UV radiation and no cathodoluminescence.

Other InformationHide

IR Spectrum:
The Raman spectrum shows a weak and strongly polarized broad OH-characteristic absorption centred at 3364 cm-1.
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 Magnesiobeltrandoite-2N3SHide

Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Cámara, F., Cossio, R., Regis, D., Ciriotti, M.E., Compagnoni, R. (2016): Magnesiobeltrandoite-2N3S, IMA 2016-073. CNMNC Newsletter No. 34, December 2016, page 1318; Mineralogical Magazine: 80: 1315–1321
Cámara, F., Cossio, R., Regis, D., Cerantola, V., Ciriotti, M.E., Compagnoni, R. (2018): Beltrandoite, a new root-name in the högbomite supergroup: the Mg end-member magnesiobeltrandoite-2N3S. European Journal of Mineralogy, 30: 545-558

Internet Links for Magnesiobeltrandoite-2N3SHide

Localities for Magnesiobeltrandoite-2N3SHide

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.
Italy (TL)
 
  • Aosta Valley
    • Valtournanche Valley
Cámara, F., Cossio, R., Regis, D., Ciriotti, M.E. and Compagnoni, R. (2016) Magnesiobeltrandoite-2N3S, IMA 2016-073. CNMNC Newsletter No. 34, December 2016, page 1318; Mineralogical Magazine, 80, 1315– 1321
Mineral and/or Locality  
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