Ottrélite
A valid IMA mineral species - grandfathered
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About Ottrélite
Formula:
(Mn2+,Fe2+,Mg)Al2(SiO4)O(OH)2
Colour:
Pistachio-green, greenish to dark grey
Hardness:
6 - 7
Crystal System:
Monoclinic
Member of:
Name:
Named by A. Descloizeaux and A.A. Damour in 1842 for the type locality of Ottré, Belgium.
Type Locality:
Mn analogue of chloritoid. Ottrélite was originally described as a Mn-rich, but not necessarily Mn-dominant chloritoid, consequently many "ottrélites" are in reality Mn-rich chloritoids, see Chloritoid best minerals article and references therein for further details.
Typically occurs in low- and medium-grade metamorphic rocks.
Monoclinic and triclinic polytypes are known.
Typically occurs in low- and medium-grade metamorphic rocks.
Monoclinic and triclinic polytypes are known.
Unique Identifiers
Mindat ID:
3043
Long-form identifier:
mindat:1:1:3043:0
GUID
(UUID V4):
(UUID V4):
211c863b-f1fa-4f26-953f-d870a99c8192
IMA Classification of Ottrélite
Approved, 'Grandfathered' (first described prior to 1959)
IMA Formula:
Mn2+Al2O(SiO4)(OH)2
First published:
1842
Classification of Ottrélite
9.AF.85
9 : SILICATES (Germanates)
A : Nesosilicates
F : Nesosilicates with additional anions; cations in [4], [5] and/or only [6] coordination
9 : SILICATES (Germanates)
A : Nesosilicates
F : Nesosilicates with additional anions; cations in [4], [5] and/or only [6] coordination
52.3.3.3
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
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
16.16.21
16 : Silicates Containing Aluminum and other Metals
16 : Aluminosilicates of Mn
16 : Silicates Containing Aluminum and other Metals
16 : Aluminosilicates of Mn
Mineral Symbols
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.
Please only use the official IMA–CNMNC symbol. Older variants are listed for historical use only.
| Symbol | Source | Reference |
|---|---|---|
| Otr | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
| Otr | The Canadian Mineralogist (2019) | The Canadian Mineralogist (2019) The Canadian Mineralogist list of symbols for rock- and ore-forming minerals (December 30, 2019). download |
Physical Properties of Ottrélite
Optical Data of Ottrélite
Type:
Biaxial (+)
RI values:
nα = 1.709 - 1.725 nβ = 1.712 - 1.726 nγ = 1.716 - 1.732
2V:
Measured: 46° to 70°, Calculated: 46° to 82°
Max Birefringence:
δ = 0.007
Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
and does not take into account mineral colouration.
Surface Relief:
High
Dispersion:
r > v strong
Chemistry of Ottrélite
Mindat Formula:
(Mn2+,Fe2+,Mg)Al2(SiO4)O(OH)2
Common Impurities:
Ca,H2O
Crystallography of Ottrélite
Crystal System:
Monoclinic
Cell Parameters:
a = 9.505(6) Å, b = 5.484(4) Å, c = 18.214(15) Å
β = 101.77(3)°
β = 101.77(3)°
Ratio:
a:b:c = 1.733 : 1 : 3.321
Unit Cell V:
929.45 ų (Calculated from Unit Cell)
Twinning:
Polysynthetic, parallel to [001].
Comment:
Space group Cc or C2/c. Pseudohexagonal.
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Near-surface Processes | |
| 23 : Subaerial aqueous alteration by non-redox-sensitive fluids (see also #47) | |
| Stage 5: Initiation of plate tectonics | <3.5-2.5 |
| 39 : High-𝑃 metamorphism (blueschist, eclogite, ultrahigh 𝑃 facies) | |
| 40 : Regional metamorphism (greenschist, amphibolite, granulite facies) |
Type Occurrence of Ottrélite
Place of Conservation of Type Material:
Muséum Nationale d’Histoire Naturelle, Paris, France, number 104.479 (type).
Reference:
Descloizeaux, A., Damour A.A. (1842) De l'ottrélite. Nouvelle espèce minérale. Annales des Mines: 2: 357-361.
Synonyms of Ottrélite
Other Language Names for Ottrélite
Relationship of Ottrélite to other Species
Member of:
Other Members of this group:
| Carboirite | FeAl2(GeO4)O(OH)2 | Tric. 1 |
| Chloritoid | (Fe2+,Mg,Mn2+)Al2(SiO4)O(OH)2 | Mon. 2/m : B2/b |
| Magnesiochloritoid | MgAl2(SiO4)O(OH)2 | Mon. 2/m : B2/b |
Common Associates
Associated Minerals Based on Photo Data:
Related Minerals - Strunz-mindat Grouping
| 9.AF. | Chegemite | Ca7(SiO4)3(OH)2 |
| 9.AF. | Barwoodite | Mn2+6Nb5+(SiO4)2O3(OH)3 |
| 9.AF. | Jingwenite-(Y) | YAlV4+(SiO4)O2(OH)2 |
| 9.AF.05 | Sillimanite | Al2(SiO4)O |
| 9.AF.05 | Xenolite | Al10Si8O31 |
| 9.AF.10 | Andalusite | Al2(SiO4)O |
| 9.AF.10 | Kanonaite | Mn3+Al(SiO4)O |
| 9.AF.15 | Kyanite | Al2(SiO4)O |
| 9.AF.20 | Mullite | Al4+2xSi2-2xO10-x |
| 9.AF.20 | Krieselite | Al2(GeO4)F2 |
| 9.AF.23 | Boromullite | Al9BSi2O19 |
| 9.AF.25 | Yoderite | Mg(Al,Fe3+)3(SiO4)2O(OH) |
| 9.AF.30 | Magnesiostaurolite | Mg(Mg,Li)3(Al,Mg)18Si8O44(OH)4 |
| 9.AF.30 | Staurolite | Fe2+2Al9Si4O23(OH) |
| 9.AF.30 | Zincostaurolite | Zn2Al9Si4O23(OH) |
| 9.AF.35 | Topaz | Al2(SiO4)(F,OH)2 |
| 9.AF.40 | Norbergite | Mg3(SiO4)F2 |
| 9.AF.45 | Alleghanyite | Mn2+5(SiO4)2(OH)2 |
| 9.AF.45 | Chondrodite | Mg5(SiO4)2F2 |
| 9.AF.45 | Reinhardbraunsite | Ca5(SiO4)2(OH,F)2 |
| 9.AF.45 | Kumtyubeite | Ca5(SiO4)2F2 |
| 9.AF.45 | Hydroxylchondrodite | Mg5(SiO4)2(OH)2 |
| 9.AF.50 | Humite | Mg7(SiO4)3F2 |
| 9.AF.50 | Manganhumite | (Mn2+,Mg)7(SiO4)3(OH)2 |
| 9.AF.50 | Unnamed (Ca-analogue of Humite) | Ca7(SiO4)4F2 |
| 9.AF.50 | Fluorchegemite | Ca7(SiO4)3F2 |
| 9.AF.50 | Unnamed (OH-analogue of humite) | Mg7(SiO4)3(OH)2 |
| 9.AF.55 | Clinohumite | Mg9(SiO4)4F2 |
| 9.AF.55 | Sonolite | Mn2+9(SiO4)4(OH)2 |
| 9.AF.55 | Hydroxylclinohumite | Mg9(SiO4)4(OH)2 |
| 9.AF.60 | Leucophoenicite | Mn2+7(SiO4)3(OH)2 |
| 9.AF.65 | Ribbeite | Mn2+5(SiO4)2(OH)2 |
| 9.AF.70 | Jerrygibbsite | Mn2+9(SiO4)4(OH)2 |
| 9.AF.75 | Franciscanite | Mn2+6(V5+,◻)2(SiO4)2(O,OH)6 |
| 9.AF.75 | Örebroite | Mn2+3(Sb5+,Fe3+)(SiO4)(O,OH)3 |
| 9.AF.75 | Welinite | Mn2+6(W6+,Mg)2(SiO4)2(O,OH)6 |
| 9.AF.75 | Scorticoite | Mn6(Sb,◻)Σ2(SiO4)2O3(OH)3 |
| 9.AF.80 | Ellenbergerite | Mg6(Mg,Ti,Zr,◻)2(Al,Mg)6Si8O28(OH)10 |
| 9.AF.85 | Chloritoid | (Fe2+,Mg,Mn2+)Al2(SiO4)O(OH)2 |
| 9.AF.85 | Magnesiochloritoid | MgAl2(SiO4)O(OH)2 |
| 9.AF.90 | Poldervaartite | CaCa[SiO3(OH)](OH) |
| 9.AF.90 | Olmiite | CaMn2+[SiO3(OH)](OH) |
| 9.AF.95 | Pilawite-(Y) | Ca2Y2Al4(SiO4)4O2(OH)2 |
Other Information
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 Ottrélite
mindat.org URL:
https://www.mindat.org/min-3043.html
Please feel free to link to this page.
Please feel free to link to this page.
Search Engines:
External Links:
References for Ottrélite
Reference List:
Localities for Ottrélite
symbol to view information about a locality.
The Locality List
- 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).
All localities listed without proper references should be considered as questionable.
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Ottré, Bihain, Vielsalm, Luxembourg, Wallonia, Belgium