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Crystal System:
Named as the Mg analogue of chloritoid. The name was originally published without IMA approval.
Monoclinic and triclinic polytypes are known.

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Classification of MagnesiochloritoidHide


9 : SILICATES (Germanates)
A : Nesosilicates
F : Nesosilicates with additional anions; cations in [4], [5] and/or only [6] coordination

52 : NESOSILICATES Insular SiO4 Groups and O,OH,F,H2O
3 : Insular SiO4 Groups and O, OH, F, and H2O with cations in [6] coordination only

16 : Silicates Containing Aluminum and other Metals
7 : Aluminosilicates of Mg

Physical Properties of MagnesiochloritoidHide

6½ on Mohs scale

Optical Data of MagnesiochloritoidHide

r < v moderate

Chemical Properties of MagnesiochloritoidHide

IMA Formula:

Crystallography of MagnesiochloritoidHide

Crystal System:
Class (H-M):
2/m - Prismatic
Space Group:
Cell Parameters:
a = 9.460(1) Å, b = 5.471(1) Å, c = 18.182(2) Å
β = 101.4(1)°
a:b:c = 1.729 : 1 : 3.323
Unit Cell V:
922.46 ų (Calculated from Unit Cell)
Common on {001}, polysynthetic.

Type Occurrence of MagnesiochloritoidHide

Other Language Names for MagnesiochloritoidHide

Relationship of Magnesiochloritoid to other SpeciesHide

Other Members of this group:
Chloritoid(Fe2+,Mg,Mn2+)Al2(SiO4)O(OH)2Mon. 2/m : B2/b

Common AssociatesHide

Associated Minerals Based on Photo Data:
Spessartine2 photos of Magnesiochloritoid associated with Spessartine on

Related Minerals - Nickel-Strunz GroupingHide

9.AF.05SillimaniteAl2(SiO4)OOrth. mmm (2/m 2/m 2/m)
9.AF.10AndalusiteAl2(SiO4)OOrth. mmm (2/m 2/m 2/m) : Pnnm
9.AF.10KanonaiteMn3+Al(SiO4)OOrth. mmm (2/m 2/m 2/m) : Pnnm
9.AF.15KyaniteAl2(SiO4)OTric. 1 : P1
9.AF.20MulliteAl4+2xSi2-2xO10-xOrth. mmm (2/m 2/m 2/m) : Pbam
9.AF.20Krieselite(Al,Ga)2(GeO4)(OH)2Orth. mmm (2/m 2/m 2/m) : Pnma
9.AF.23BoromulliteAl9BSi2O19Orth. mm2 : Cmc21
9.AF.25YoderiteMg(Al,Fe3+)3(SiO4)2O(OH)Mon. 2/m : P21/m
9.AF.30MagnesiostauroliteMg(Mg,Li)3(Al,Mg)18Si8O44(OH)4Mon. 2/m : B2/m
9.AF.30StauroliteFe2+2Al9Si4O23(OH)Mon. 2/m : B2/m
9.AF.30ZincostauroliteZn2Al9Si4O23(OH)Mon. 2/m : B2/m
9.AF.35TopazAl2(SiO4)(F,OH)2Orth. mmm (2/m 2/m 2/m)
9.AF.40NorbergiteMg3(SiO4)(F,OH)2Orth. mmm (2/m 2/m 2/m)
9.AF.45AlleghanyiteMn2+5(SiO4)2(OH)2Mon. 2/m : P21/b
9.AF.45Chondrodite(Mg,Fe2+)5(SiO4)2(F,OH)2Mon. 2/m : P21/b
9.AF.45ReinhardbraunsiteCa5(SiO4)2(OH,F)2Mon. 2/m : P21/b
9.AF.45KumtyubeiteCa5(SiO4)2F2Mon. 2/m : P21/b
9.AF.45HydroxylchondroditeMg5(SiO4)2(OH)2Mon. 2/m : P21/b
9.AF.50Humite(Mg,Fe2+)7(SiO4)3(F,OH)2Orth. mmm (2/m 2/m 2/m)
9.AF.50Unnamed (Ca-analogue of Humite)Ca7(SiO4)4F2Orth. mmm (2/m 2/m 2/m)
9.AF.55HydroxylclinohumiteMg9(SiO4)4(OH)2Mon. 2/m
9.AF.60LeucophoeniciteMn2+7(SiO4)3(OH)2Mon. 2/m : P21/b
9.AF.70JerrygibbsiteMn2+9(SiO4)4(OH)2Orth. mmm (2/m 2/m 2/m) : Pbcn
9.AF.75WeliniteMn2+6(W6+,Mg)2(SiO4)2(O,OH)6Trig. 3 : P3
9.AF.85Chloritoid(Fe2+,Mg,Mn2+)Al2(SiO4)O(OH)2Mon. 2/m : B2/b
9.AF.90PoldervaartiteCaCa[SiO3(OH)](OH)Orth. mmm (2/m 2/m 2/m) : Pbca
9.AF.90OlmiiteCaMn2+[SiO3(OH)](OH)Orth. mmm (2/m 2/m 2/m) : Pbca

Related Minerals - Dana Grouping (8th Ed.)Hide,Mg,Mn2+)Al2(SiO4)O(OH)2Mon. 2/m : B2/bélite(Mn2+,Fe2+,Mg)Al2(SiO4)O(OH)2Mon. 2/m : P21/b 2/m : P21/b

Related Minerals - Hey's Chemical Index of Minerals GroupingHide

16.7.2SapphirineMg4(Mg3Al9)O4[Si3Al9O36]Mon. 2/m : P21/b
16.7.3Sapphirine-1A(Mg,Al,Fe2+)8[(Al,Si,Fe3+)6O18]O2Tric. 1 : P1
16.7.6Palygorskite(Mg,Al)5(Si,Al)8O20(OH)2 · 8H2OMon. 2/m : B2/m
16.7.7SaponiteCa0.25(Mg,Fe)3((Si,Al)4O10)(OH)2 · nH2OMon.
16.7.8AliettiteCa0.2Mg6((Si,Al)8O20)(OH)4 · 4H2OMon.
16.7.9Montmorillonite(Na,Ca)0.33(Al,Mg)2(Si4O10)(OH)2 · nH2OMon. 2/m : B2/m

Other InformationHide

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 MagnesiochloritoidHide

Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Chopin, C. and Schreyer, W. (1983) Magnesio-carpholite and magnesiochloritoid: two index minerals of pelitic blueschists and their preliminary phase relations n the model system MgO-Al2O3-SiO2-H2O. American Journal of Science: 283-A: 72-96.
Chopin, C. (1983): Magnesiochloritoid, a key-mineral for the petrogenesis of high-grade pelitic blueschists. Bulletin de Minéralogie 106, 715-717.
American Mineralogist (1985): 70: 216-217.
Ivaldi, G., Catti, M., Ferraris, G. (1988): Crystal structure at 25 and 700 °C of magnesiochloritoid from a high-pressure assemblage (Monte Rosa). American Mineralogist 73, 358-364.
Comodi, P., Mellini, M., Zanazzi, P.F. (1992): Magnesiochloritoid: Compressibility and high pressure structure refinement. Physics and Chemistry of Minerals 18, 483-490.

Internet Links for MagnesiochloritoidHide

Localities for MagnesiochloritoidHide

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.
  • Jiangsu Province
    • Lianyungang Prefecture
      • Donghai Co.
        • Zhimafang
Zhang, R.Y., Liou, J.G., and Zheng, J.P. (2004): Contributions to Mineralogy and Petrology 147, 21-31.
  • Aosta Valley
    • Saint-Marcel
Piccoli, G.C., Maletto, G., Bosio, P., Lombardo, B. (2007): Minerali del Piemonte e della Valle d'Aosta. Associazione Amici del Museo "F. Eusebio" Alba, Ed., Alba (Cuneo) 607 pp.
  • Piedmont
    • Cuneo Province
Lithos, 41: 37-57.
      • Po Valley
        • Monviso
Messiga et al. : "Cr-rich Magnesiochloritoid Eclogites from the Monviso ophiolites (Western Alps Italy)", Journal of Metamorphic Geology, Vol 17, Issue 3, p. 287, May 1999.
      • Varaita Valley
        • Brossasco
Piccoli, G.C., Maletto, G., Bosio, P., Lombardo, B. (2007). Minerali del Piemonte e della Valle d'Aosta. Associazione Amici del Museo "F. Eusebio" Alba, Ed., Alba (Cuneo) 607 pp.
  • Andalusia
    • Granada
      • Otívar
Eur. J. Mineral. , 1989, 1, pp. 139-142..
  • Madrid
    • La Hiruela
  • Wallis (Valais)
    • Zermatt - Saas Fee area
      • Matt Valley
Stalder, H. A., Wagner, A., Graeser, S. and Stuker, P. (1998): "Mineralienlexikon der Schweiz", Wepf (Basel), p. 261.
        • Zermatt
          • Gorner glacier area
            • Stockhorn
Cont. to Mineralogy and Petrology 87:388-398
      • Saas Valley
        • Saas-Almagell
          • Allalin area
Bearth, P. (1963): Chloritoid und Paragonit aus der Ophiolit-Zone von Zermatt-Saas Fee. Schweizerische Mineralogische und Petrographische Mitteilungen, 43, 269-286; Stalder, H.A., Wagner, A., Graeser, S., Stuker, P. (1998): Mineralienlexikon der Schweiz. Wepf Verlag, Basel, pages 261-262; Roth, Ph. (2007): Minerals first discovered in Switzerland and minerals named after Swiss individuals. Philippe Roth, Ed., Zurich, 239 pp.
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