Where it forms, where it's found
- Geological setting
Magnesian chloritites of a metamorphosed layered mafic complex
- Type locality
- Marmore stream
- Torgnon
- Aosta Valley
- Italy
45.8267°, 7.5808°
1recorded occurrences
Physical
Optical
- Optical type
- Uniaxial (-)
- Pleochroism
- Weak
With ε = deep reddish brown (along c axis) and ω = reddish brown (⊥ c). Absorption is E > O.
- UV response
- No fluorescence under UV radiation and no cathodoluminescence.
- Notes
An estimated mean refractive index of ca. 1.80.
Crystallography
- Space group
- #84
- Cell parameters
- a = 5.7226(3) Å · c = 23.0231(9) Å
- Type-locality form
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
Chemical composition
Synonyms
- IMA2016-073
- Magnesiobeltrandoiet-2N3S
In other languages
- German
- IMA 2016-073 · Magnesiobeltrandoit-2N3S
Classification
Strunz
10th ed.4.CB.20
- 4OxidesClass
- 4.CMetal: Oxygen = 2: 3,3: 5, and similarDivision
- 4.CBWith medium-sized cationsGroup
- 4.CB.20Magnesiobeltrandoite-2N3SSpecies
Group, growth & confusion
Literature, links & citation
Citations
- 2016Hålenius, U., Hatert, F., Pasero, M., Mills, S. J. (2016) New minerals and nomenclature modifications approved in 2016, CNMNC Newsletter No 34. Mineralogical Magazine, 80 (7) 1315-1321 doi:10.1180/minmag.2016.080.086DOI: 10.1180/minmag.2016.080.086
- 2018Cámara, Fernando, Cossio, Roberto, Regis, Daniele, Cerantola, Valerio, Ciriotti, Marco E., Compagnoni, Roberto (2018) Beltrandoite, a new root-name in the högbomite supergroup: the Mg end-member magnesiobeltrandoite-2N3S. European Journal of Mineralogy, 30 (3). 545-558 doi:10.1127/ejm/2017/0029-2692 DOI: 10.1127/ejm/2017/0029-2692
Cite this entry
@misc{mineral2026,
author = {Mineral Index editorial board},
title = {Magnesiobeltrandoite-2N3S — Mineral Index},
year = {2026},
url = {https://mineralindex.org/minerals/magnesiobeltrandoite-2n3s-50780},
note = {Accessed 2026-05-11}
}