Magnesiochloritoid (original) (raw)

A valid IMA mineral species

About MagnesiochloritoidHide

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Formula:

MgAl2O(SiO4)(OH)2

Colour:

Colourless in thin section, pale blue-green in smaller crystals and dark blue in larger crystals

Crystal System:

Monoclinic

Name:

Named as the Mg analogue of chloritoid. The name was originally published without IMA approval.

Monoclinic and triclinic polytypes are known.

Unique IdentifiersHide

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Long-form identifier:

mindat:1:1:2497:2

2f2ed48c-3b42-4191-a1ec-b8fc3b03df13

IMA Classification of MagnesiochloritoidHide

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IMA status notes:

Renamed by the IMA

Approval history:

Renamed by the IMA in 1987. Other names such as magnesio-chloritoid, Mg-chloritoid and sismondine were recommended to be discarded in favor of magnesiochloritoid.

Type description reference:

Chopin, Christian, Seidel, Eberhard, Theye, Thomas, Ferraris, Giovanni, Ivaldi, Gabriella, Catti, Michele (1992) Magnesiochloritoid, and the Fe-Mg series in the chloritoid group. European Journal of Mineralogy, 4 (1) 67-76 doi:10.1127/ejm/4/1/0067

Classification of MagnesiochloritoidHide

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9.AF.85

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

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

16.7.4

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

Mineral SymbolsHide

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As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.

Please only use the official IMA–CNMNC symbol. Older variants are listed for historical use only.

Physical Properties of MagnesiochloritoidHide

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Colour:

Colourless in thin section, pale blue-green in smaller crystals and dark blue in larger crystals

Cleavage:

Perfect
{001} perfect (by analogy to choritoid)

Density:

3.25(2) g/cm3 (Measured)

Comment:

Measured in heavy liquids.

Optical Data of MagnesiochloritoidHide

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RI values:

_n_α = 1.687(2) _n_β = 1.690(2) _n_γ = 1.702(2)

2V:

Measured: 40° to 50°, Calculated: 53°

δ = 0.015

Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.

Dispersion:

r < v moderate

Comments:

Very faint, light blue, grey blue, yellowish.

Comments:

Refractive indices from Chopin et al. (1992) for type material.

Chemistry of MagnesiochloritoidHide

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Mindat Formula:

MgAl2O(SiO4)(OH)2

Crystallography of MagnesiochloritoidHide

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Crystal System:

Monoclinic

Class (H-M):

2/m - Prismatic

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 V:

922.46 ų (Calculated from Unit Cell)

Twinning:

Common on {001}, polysynthetic.

Crystal StructureHide

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ID	Species	Reference	Link	Year	Locality	Pressure (GPa)	Temp (K)
0001139	Magnesiochloritoid	Ivaldi G, Catti M, Ferraris G (1988) Crystal structure at 25 and 700 C of magnesiochloritoid from a high-pressure assemblage (Monte Rosa) Sample at 25 C American Mineralogist 73 358-364		1988	0	293
0001140	Magnesiochloritoid	Ivaldi G, Catti M, Ferraris G (1988) Crystal structure at 25 and 700 C of magnesiochloritoid from a high-pressure assemblage (Monte Rosa) Sample at 700 C American Mineralogist 73 358-364		1988	0	293
0007686	Magnesiochloritoid	Comodi P, Mellini M, Zanazzi P F (1992) Magnesiochloritoid: compressibility and high pressure structure refinement Physics and Chemistry of Minerals 18 483-490	1992	0.0001	293
0007687	Magnesiochloritoid	Comodi P, Mellini M, Zanazzi P F (1992) Magnesiochloritoid: compressibility and high pressure structure refinement Physics and Chemistry of Minerals 18 483-490	1992	0.0001	293
0007688	Magnesiochloritoid	Comodi P, Mellini M, Zanazzi P F (1992) Magnesiochloritoid: compressibility and high pressure structure refinement Physics and Chemistry of Minerals 18 483-490	1992	3.4	293

CIF Raw Data - click here to close

X-Ray Powder DiffractionHide

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Powder Diffraction Data:

Comments:

Data from Chopin et al. (1992).

Geological EnvironmentHide

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Type Occurrence of MagnesiochloritoidHide

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General Appearance of Type Material:

Dark-blue millimetric crystals.

Place of Conservation of Type Material:

National School of Mines, Paris, France.
Museum of Natural Science, Torino, Italy.

Geological Setting of Type Material:

In magnesian pelitic rocks (or magnesian microsystems in mafic rocks) metamorphosed at high pressures, near 15 kbar or more.

Associated Minerals at Type Locality:

Reference:

Chopin, C., Seidel, E., Theye, T., Ferraris, G., Ivaldi, G., Catti, M. (1992) Magnesiochloritoid, and the Fe-Mg series in the chloritoid group. European Journal of Mineralogy, 4, 67-76.

Other Language Names for MagnesiochloritoidHide

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Relationship of Magnesiochloritoid to other SpeciesHide

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Other Members of this group:

Common AssociatesHide

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Associated Minerals Based on Photo Data:

Related Minerals - Strunz-mindat GroupingHide

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Other InformationHide

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Health Risks:

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

Internet Links for MagnesiochloritoidHide

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References for MagnesiochloritoidHide

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Reference List:

Dunn, Pete J., Chao, George Y., Fleischer, Michael, Ferraiolo, James A., Langley, Richard H., Pabst, Adolf, Zilczer, Janet A. (1985) New mineral names. American Mineralogist, 70 (1-2) 214-221

Chopin, Christian, Seidel, Eberhard, Theye, Thomas, Ferraris, Giovanni, Ivaldi, Gabriella, Catti, Michele (1992) Magnesiochloritoid, and the Fe-Mg series in the chloritoid group. European Journal of Mineralogy, 4 (1) 67-76 doi:10.1127/ejm/4/1/0067

Localities for MagnesiochloritoidHide

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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

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- This locality has map coordinates listed. - This locality has estimated coordinates. ⓘ - Click for references and 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 (e.g. from pseudomorphs).

All localities listed without proper references should be considered as questionable.