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Protoenstatite

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Formula:
Mg2Si2O6
Crystal System:
Orthorhombic
First discovered in Oregon sunstones with unusual pleochroic/dichroic red to green coloration. The crystallographically oriented nanocrystals of protoenstatite and clinoenstatite in association with copper nanocrystals are responsible for the unusual green and “watermelon” coloration of this gemstone, which is a labradorite.


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Classification of ProtoenstatiteHide

Approved
Approval Year:
2016
First Published:
2017
9.DA.

9 : SILICATES (Germanates)
D : Inosilicates
A : Inosilicates with 2-periodic single chains, Si2O6; pyroxene family

Pronounciation of ProtoenstatiteHide

Pronounciation:
PlayRecorded byCountry
Jolyon & Katya RalphUnited Kingdom

Chemical Properties of ProtoenstatiteHide

Formula:
Mg2Si2O6

Crystallography of ProtoenstatiteHide

Crystal System:
Orthorhombic
Class (H-M):
mmm (2/m 2/m 2/m) - Dipyramidal
Space Group:
Pbcn
Setting:
Pbcn
Cell Parameters:
a = 9.25(1) Å, b = 8.78(1) Å, c = 5.32(1) Å
Ratio:
a:b:c = 1.054 : 1 : 0.606
Unit Cell V:
432.06 ų (Calculated from Unit Cell)

X-Ray Powder DiffractionHide

Powder Diffraction Data:
d-spacingIntensity
3.243(20)
3.184(47)
3.180(100)
2.909(38)
2.732(32)
2.556(22)
2.471(24)
2.306(33)
Comments:
From Type Description.

Type Occurrence of ProtoenstatiteHide

Place of Conservation of Type Material:
Type material is deposited in the mineralogical collections of the Geology Museum, Department of Geoscience, University of Wisconsin-Madison, 1215 West Dayton Street, Madison, WI 53706, USA, catalogue numbers UWGM 3538 and UWGM 3539
Empirical Formula of Type Material:
(Mg1.17Fe0.43Al0.26Ca0.03Na0.10Ti0.012.00(Si1.83Al0.172.00O6
Reference:
Xu, H., Hill, T.R., Konishi, H., Farfan, G. (2017): Protoenstatite: A new mineral in Oregon sunstones with “watermelon” colors. American Mineralogist: 102: 2146-2149

Synonyms of ProtoenstatiteHide

Relationship of Protoenstatite to other SpeciesHide

Other Members of this group:
Donpeacorite(Mn2+,Mg)Mg[SiO3]2Orth.
EnstatiteMgSiO3Orth. mmm (2/m 2/m 2/m) : Pbca
ensteniteA series name for the orthopyroxenes of the MgSiO3 -FeSiO3 isomorphous series (enstatite - ...
FerrosiliteFeSiO3Orth. mmm (2/m 2/m 2/m) : Pbca

Related Minerals - Nickel-Strunz GroupingHide

9.DA.05Donpeacorite(Mn2+,Mg)Mg[SiO3]2Orth.
9.DA.05EnstatiteMgSiO3Orth. mmm (2/m 2/m 2/m) : Pbca
9.DA.05FerrosiliteFeSiO3Orth. mmm (2/m 2/m 2/m) : Pbca
9.DA.10ClinoenstatiteMgSiO3Mon. 2/m : P21/b
9.DA.10ClinoferrosiliteFe2+SiO3Mon. 2/m : P21/b
9.DA.10KanoiteMn2+(Mg,Mn2+)Si2O6Mon. 2/m : P21/b
9.DA.10Pigeonite(CaxMgyFez)(Mgy1Fez1)Si2O6Mon. 2/m : P21/b
9.DA.15Augite(CaxMgyFez)(Mgy1Fez1)Si2O6Mon. 2/m : B2/b
9.DA.15DiopsideCaMgSi2O6Mon. 2/m : B2/b
9.DA.15EsseneiteCaFe3+[AlSiO6]Mon. 2/m : B2/b
9.DA.15HedenbergiteCaFe2+Si2O6Mon. 2/m : B2/b
9.DA.15JohannseniteCaMn2+Si2O6Mon. 2/m : B2/b
9.DA.15PetedunniteCa(Zn,Mn2+,Mg,Fe2+)Si2O6Mon.
9.DA.15DavisiteCaScAlSiO6Mon. 2/m : B2/b
9.DA.15KushiroiteCaAl[AlSiO6]Mon. 2/m : B2/b
9.DA.15GrossmaniteCaTi3+ AlSiO6Mon. 2/m : B2/b
9.DA.20Aegirine-augite(NaaCabFe2+cMgd)(Fe3+eAlfFe2+gMgh)Si2O6Mon. 2/m : B2/b
9.DA.20Omphacite(NaaCabFe2+cMgd)(AleFe3+fFe2+gMgh)Si2O6Mon. 2/m
9.DA.25AegirineNaFe3+Si2O6Mon. 2/m : B2/b
9.DA.25JadeiteNa(Al,Fe3+)Si2O6Mon.
9.DA.25JervisiteNaSc3+Si2O6Mon.
9.DA.25KosmochlorNaCrSi2O6Mon.
9.DA.25NamansiliteNaMn3+Si2O6Mon.
9.DA.25NatalyiteNaV3+Si2O6Mon.
9.DA.30SpodumeneLiAlSi2O6Mon.

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 ProtoenstatiteHide

Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Xu, H. and Hill, T.R. (2017) Protoenstatite, IMA 2016-117. CNMNC Newsletter No. 37, June 2017, page 738; Mineralogical Magazine: 81: 737–742.
Xu, H., Hill, T.R., Konishi, H., Farfan, G. (2017): Protoenstatite: A new mineral in Oregon sunstones with “watermelon” colors. American Mineralogist: 102: 2146-2149

Internet Links for ProtoenstatiteHide

Localities for ProtoenstatiteHide

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.
USA (TL)
 
  • Oregon
    • Lake Co.
      • Plush
Xu, H. and Hill, T.R. (2017) Protoenstatite, IMA 2016-117. CNMNC Newsletter No. 37, June 2017, page 738; Mineralogical Magazine, 81, 737–742.; Xu, H., Hill, T.R., Konishi, H., Farfan, G. (2017): Protoenstatite: A new mineral in Oregon sunstones with “watermelon” colors. American Mineralogist, 102, 2146-2149
Mineral and/or Locality  
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