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Magnesiochloritoid

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Big Photo

Prabornaz Mine (ex Praborna Mine), Saint-Marcel, Aosta Valley, Italy
© Coleccion- Agudo Espinosa




Formula:
MgAl
 
2
(SiO
 
4
)O(OH)
 
2
System:MonoclinicHardness:6½
Member of:Chloritoid Group
Name:Named as the Mg analogue of chloritoid.


Monoclinic and triclinic polytypes are known.


Classification of Magnesiochloritoid

IMA status:Approved
Strunz 8th edition ID:8/B.24-10
Nickel-Strunz 10th (pending) edition ID:9.AF.85

9 : SILICATES (Germanates)
A : Nesosilicates
F : Nesosilicates with additional anions; cations in [4], [5] and/or only [6] coordination
Dana 8th edition ID:52.3.3.2

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
Hey's CIM Ref.:16.7.4

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

Type Locality:Allalin glacier, Allalin area, Saas Almagell, Saas Valley, Zermatt - Saas Fee area, Wallis (Valais), Switzerland

Physical Properties of Magnesiochloritoid

Hardness (Mohs):6½

Crystallography of Magnesiochloritoid

Crystal System:Monoclinic
Class (H-M):2/m - Prismatic
Space Group:B2/b {B1 1 2/b} {C2/c} {C1 2/c 1}
Space Group Setting:C2/c
Cell Parameters:a = 9.460(1) Å, b = 5.471(1) Å, c = 18.182(2) Å
β = 101.4(1)°
Ratio:a:b:c = 1.729 : 1 : 3.323
Unit Cell Volume:V 922.46 ų (Calculated from Unit Cell)
Z:4
Twinning:Common on {001}, polysynthetic.

Optical Data of Magnesiochloritoid

Type:Biaxial
Dispersion:r < v moderate

Chemical Properties of Magnesiochloritoid

Formula:
MgAl
 
2
(SiO
 
4
)O(OH)
 
2
Essential elements:Al, H, Mg, O, Si
All elements listed in formula:Al, H, Mg, O, Si

Relationship of Magnesiochloritoid to other Species

Member of:Chloritoid Group
Other Members of Group:

- +
Carboirite
FeAl
 
2
(GeO
 
4
)O(OH)
 
2
Chloritoid
(Fe
2+
 
,Mg,Mn
2+
 
)Al
 
2
(SiO
 
4
)O(OH)
 
2
Ottrélite
(Mn
2+
 
,Fe
2+
 
,Mg)Al
 
2
(SiO
 
4
)O(OH)
 
2
Related Minerals - Nickel-Strunz Grouping):

- +
9.AF.05Sillimanite
Al
 
2
(SiO
 
4
)O
9.AF.10Andalusite
Al
 
2
(SiO
 
4
)O
9.AF.10Kanonaite
Mn
3+
 
Al(SiO
 
4
)O
9.AF.15Kyanite
Al
 
2
(SiO
 
4
)O
9.AF.20Mullite
Al
 
4+2x
Si
 
2-2x
O
 
10-x
9.AF.20Krieselite
(Al,Ga)
 
2
(GeO
 
4
)(OH)
 
2
9.AF.23Boromullite
Al
 
9
BSi
 
2
O
 
19
9.AF.25Yoderite
Mg(Al,Fe
3+
 
)
 
3
(SiO
 
4
)
 
2
O(OH)
9.AF.30Magnesiostaurolite
(Mg,Li,Fe
2+
 
)
 
1.5-2
Al
 
9
(SiO
 
4
)
 
4
O
 
6
(OH)
 
2
9.AF.30Staurolite
(Fe
2+
 
,Mg,Zn)
 
1.5-2
Al
 
9
(SiO
 
4
)
 
4
O
 
6
(OH,O)
 
2
9.AF.30Zincostaurolite
(Zn,Li,Fe
2+
 
,Mg)
 
1.5-2
Al
 
9
(SiO
 
4
)
 
4
O
 
6
(OH)
 
2
9.AF.35Topaz
Al
 
2
(SiO
 
4
)(F,OH)
 
2
9.AF.40Norbergite
Mg
 
3
(SiO
 
4
)(F,OH)
 
2
9.AF.45Alleghanyite
Mn
2+
5
(SiO
 
4
)
 
2
(OH)
 
2
9.AF.45Chondrodite
(Mg,Fe
2+
 
)
 
5
(SiO
 
4
)
 
2
(F,OH)
 
2
9.AF.45Reinhardbraunsite
Ca
 
5
(SiO
 
4
)
 
2
(OH,F)
 
2
9.AF.45Kumtyubeite
Ca
 
5
(SiO
 
4
)
 
2
F
 
2
9.AF.45Hydroxylchondrodite
Mg
 
5
(SiO
 
4
)
 
2
(OH)
 
2
9.AF.50Humite
(Mg,Fe
2+
 
)
 
7
(SiO
 
4
)
 
3
(F,OH)
 
2
9.AF.50Manganhumite
(Mn
2+
 
,Mg)
 
7
(SiO
 
4
)
 
3
(OH)
 
2
9.AF.50Unnamed (Ca-analogue of Humite)
Ca
 
7
(SiO
 
4
)
 
4
F
 
2
9.AF.55Clinohumite
(Mg,Fe
2+
 
)
 
9
(SiO
 
4
)
 
4
(F,OH)
 
2
9.AF.55Sonolite
Mn
2+
9
(SiO
 
4
)
 
4
(OH,F)
 
2
9.AF.55Hydroxylclinohumite
Mg
 
9
(SiO
 
4
)
 
4
(OH,F)
 
2
9.AF.60Leucophoenicite
Mn
2+
7
(SiO
 
4
)
 
3
(OH)
 
2
9.AF.65Ribbeite
(Mn
2+
 
,Mg)
 
5
(SiO
 
4
)
 
2
(OH)
 
2
9.AF.70Jerrygibbsite
Mn
2+
9
(SiO
 
4
)
 
4
(OH)
 
2
9.AF.75Franciscanite
Mn
2+
6
(V
5+
 
,☐)
 
2
(SiO
 
4
)
 
2
(O,OH)
 
6
9.AF.75Örebroite
Mn
2+
3
(Fe
3+
 
,Sb
5+
 
)(SiO
 
4
)(O,OH)
 
3
9.AF.75Welinite
Mn
2+
6
(W
6+
 
,Mg)
 
2
(SiO
 
4
)
 
2
(O,OH)
 
6
9.AF.80Ellenbergerite
Mg
 
6
(Mg,Ti,Zr,◻)
 
2
(Al,Mg)
 
6
Si
 
8
O
 
28
(OH)
 
10
9.AF.85Chloritoid
(Fe
2+
 
,Mg,Mn
2+
 
)Al
 
2
(SiO
 
4
)O(OH)
 
2
9.AF.85Ottrélite
(Mn
2+
 
,Fe
2+
 
,Mg)Al
 
2
(SiO
 
4
)O(OH)
 
2
9.AF.90Poldervaartite
CaCa[SiO
 
3
(OH)](OH)
9.AF.90Olmiite
CaMn
2+
 
[SiO
 
3
(OH)](OH)
Related Minerals - Hey's Index Grouping:

- +
16.7.1Pyrope
Mg
 
3
Al
 
2
(SiO
 
4
)
 
3
16.7.2Sapphirine
(Mg,Fe)
 
4-x
Al
 
4+x
[Al
 
4+x
Si
 
2-x
O
 
18
]O
 
2
16.7.3Sapphirine-1A
(Mg,Al,Fe
2+
 
)
 
8
[(Al,Si,Fe
3+
 
)
 
6
O
 
18
]O
 
2
16.7.5Kulkeite
Mg
 
8
Al(AlSi
 
7
O
 
20
)(OH)
 
10
16.7.6Palygorskite
(Mg,Al)
 
5
(Si,Al)
 
8
O
 
20
(OH)
 
2
 · 8H
 
2
O
16.7.7Saponite
Ca
 
0.25
(Mg,Fe)
 
3
((Si,Al)
 
4
O
 
10
)(OH)
 
2
 · nH
 
2
O
16.7.8Aliettite
Ca
 
0.2
Mg
 
6
((Si,Al)
 
8
O
 
20
)(OH)
 
4
 · 4H
 
2
O
16.7.9Montmorillonite
(Na,Ca)
 
0.33
(Al,Mg)
 
2
(Si
 
4
O
 
10
)(OH)
 
2
 · nH
 
2
O
16.7.10Baumite
(Mg,Al,Mn,Zn,Fe)
 
3
(Si,Al)
 
2
O
 
5
(OH)
 
4

Other Names for Magnesiochloritoid

Other Languages:
Russian:Магнезиохлоритоид
Simplified Chinese:镁硬绿泥石

Other Information

Health Warning:No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

References for Magnesiochloritoid

Reference List:

- +
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.

American Mineralogist (1985): 70: 216-217.

American Mineralogist (1988): 73: 358-364.

Internet Links for Magnesiochloritoid

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  • Raman and XRD data at RRUFF project
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  • Magnesiochloritoid details from Handbook of Mineralogy (PDF)
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    • Localities for Magnesiochloritoid

    The 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.
    Hide Locality List
    (TL) indicates type locality. ? indicates mineral may be doubtful at this locality. All other localities listed without reference should be considered as uncertain and unproven until references can be found.
    China
     
    • 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.
    Italy
     
    • 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.
          • 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.
        • 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.
    Spain
     
    • Andalusia
      • Granada
        • Otívar
    		Eur. J. Mineral. , 1989, 1, pp. 139-142..
    Switzerland
     
    • 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
    		Stalder, H. A., Wagner, A., Graeser, S. and Stuker, P. (1998): "Mineralienlexikon der Schweiz", Wepf (Basel), p. 261-262.
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