Enstatite

Caspar quarry, Ettringer Bellerberg Mt. (Bellberg Mt.; Bellenberg Mt.; Billenberg Mt.; Boilenberg Mt.), Bellerberg volcano, Ettringen, Mayen, Eifel Mts, Rhineland-Palatinate, Germany
© luigi chiappino

Show Enstatite Photos (81)

Formula:

[SiO

]

System:

Orthorhombic

Colour:

White, yellowish green, ...

Lustre:

Vitreous, Pearly

Hardness:

5 - 6

Name:

From the Greek enstates - "opponent" for refractory nature under blowpipe flame.

Dimorph of:

Clinoenstatite

Enstatite Group. Enstatite-Ferrosilite Series.

Classification of Enstatite

IMA status:

Valid - first described prior to 1959 (pre-IMA) - "Grandfathered"

Strunz 8th edition ID:

8/F.02-10

Nickel-Strunz 10th (pending) edition ID:

9.DA.05

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

Dana 8th edition ID:

65.1.2.1

65 : INOSILICATES Single-Width,Unbranched Chains,(W=1)
1 : Single-Width Unbranched Chains, W=1 with chains P=2

Hey's CIM Ref.:

14.4.2

14 : Silicates not Containing Aluminum
4 : Silicates of Mg

mindat.org URL:

http://www.mindat.org/min-1384.html
Please feel free to link to this page.

Occurrences of Enstatite

Geological Setting:

Magmatic mafic rocks

Physical Properties of Enstatite

Lustre:

Vitreous, Pearly

Diaphaneity (Transparency):

Translucent, Opaque

Comment:

Pearly on cleavage

Colour:

White, yellowish green, brown, greenish white or grey, olive-green

Streak:

Grey to white

Hardness (Mohs):

5 - 6

Tenacity:

Brittle

Cleavage:

Distinct/Good
Good on {210}

Parting:

on {100} and {010}

Fracture:

Irregular/Uneven

Density (measured):

3.2 - 3.9 g/cm³

Density (calculated):

3.189 g/cm³

Crystallography of Enstatite

Crystal System:

Orthorhombic

Class (H-M):

mmm (2/m 2/m 2/m) - Dipyramidal

Space Group:

Pbca {P2₁/b 2₁/c 2₁/a}

Cell Parameters:

a = 18.23Å, b = 8.84Å, c = 5.19Å

Ratio:

a:b:c = 2.062 : 1 : 0.587

Unit Cell Volume:

V 836.39 Å³ (Calculated from Unit Cell)

Morphology:

Prismatic crystals

Twinning:

Simple and lamellar on {100}

Crystal Atlas:

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Enstatite no.12 - Goldschmidt (1913-1926)

Enstatite no.67 - Goldschmidt (1913-1926)

About Crystal Atlas

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The mindat.org Crystal Atlas allows you to view a selection of crystal drawings of real and idealised crystal forms for this mineral and, in certain cases, 3d rotating crystal objects. You need Java to see these. You can download Java for free - click here to download Java

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X-Ray Powder Diffraction:

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Radiation - Copper Kα
Data courtesy of RRUFF project at University of Arizona, used with permission.

Optical Data of Enstatite

Type:

Biaxial (+)

RI values:

n_α = 1.650 - 1.668 n_β = 1.652 - 1.673 n_γ = 1.659 - 1.679

2V:

Measured: 54° to 90°, Calculated: 58° to 86°

Maximum Birefringence:

δ = 0.009 - 0.011

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

Surface Relief:

Moderate

Dispersion:

r < v weak

Chemical Properties of Enstatite

Formula:

[SiO

]

Essential elements:

Mg, O, Si

All elements listed in formula:

Mg, O, Si

Common Impurities:

Fe,Ca,Al,Co,Ni,Mn,Ti,Cr,Na,K

Relationship of Enstatite to other Species

Series:

Forms a series with Ferrosilite (see here)

Member of Group:

Orthopyroxene Subgroup

9.DA.05

Donpeacorite

(Mn

,Mg)Mg[SiO

]

9.DA.05

Ferrosilite

[SiO

]

9.DA.10

Clinoenstatite

[Si

]

9.DA.10

Clinoferrosilite

(Fe

,Mg)[Si

]

9.DA.10

Kanoite

(Mg,Mn

)[Si

]

9.DA.10

Pigeonite

(Mg,Fe

,Ca)(Mg,Fe

)[Si

]

9.DA.15

Augite

(Ca,Na)(Mg,Fe

,Al,Fe

,Ti)[(Si,Al)

]

9.DA.15

Diopside

CaMg[Si

]

9.DA.15

Esseneite

CaFe

[AlSiO

]

9.DA.15

Hedenbergite

CaFe

[Si

]

9.DA.15

Johannsenite

CaMn

[Si

]

9.DA.15

Petedunnite

Ca(Zn,Mn

,Mg,Fe

)[Si

]

9.DA.15

Davisite

CaScAlSiO

9.DA.15

Kushiroite

CaAl[AlSiO

]

9.DA.15

Grossmanite

CaTi

AlSiO

9.DA.20

Aegirine-augite

(Na,Ca)(Fe

,Fe

,Mg,Al)Si

9.DA.20

Omphacite

(Ca,Na)(Mg,Al)[Si

]

9.DA.25

Aegirine

NaFe

[Si

]

9.DA.25

Jadeite

Na(Al,Fe

)[Si

]

9.DA.25

Jervisite

(Na,Ca,Fe

)(Sc,Mg,Fe

)[Si

]

9.DA.25

Kosmochlor

NaCr[Si

]

9.DA.25

Namansilite

NaMn

[Si

]

9.DA.25

Natalyite

Na(V

,Cr)[Si

]

9.DA.30

Spodumene

LiAl[Si

]

14.4.1

Forsterite

[SiO

]

14.4.3

Clinoenstatite

[Si

]

14.4.4

Chrysotile

(OH)

14.4.5

14.4.6

14.4.7

14.4.8

[(OH)

|Si

]

14.4.9

Talc

(OH)

14.4.10

Spadaite

MgSiO

(OH)

·H

14.4.11

Sepiolite

(OH)

·6H

14.4.12

Loughlinite

·8H

14.4.13

Eifelite

KNa

14.4.14

Stevensite

(Ca,Na)

(OH)

14.4.15

Antigorite

(Mg,Fe

)

[(OH)

|Si

]

14.4.16

Magnesio-anthophyllite

Other Names for Enstatite

Synonyms:

Amblystegite	Chladnite	Enstadite	Ficinite	O-enstatite
Orthobronzite	Orthoenstatite	Paulite	Peckhamite	Protobastite
Shepardite	Shepardite (of Rose)	Victorite

Other Languages:

German:	Amblystegit Chladnit Cladnit Enstadit Enstatit Ficinit O-enstatit Orthobronzit Orthoenstatit Paulit Peckhamit Protobastit Shepardit Victorit
Russian:	Энстатит
Spanish:	Amblystegita Chladnita Enstadita Enstatita Ficinita Orthobronzita Orthoenstatita Paulita Peckhamita Protobastita Shepardita Victorita

Varieties:

Bronzite

Lime-Bronzite

Vanadinbronzite

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 Enstatite

Reference List:

Klaproth, M.H. (1810): Chemische Untersuchung des Bronzits, Beiträge zur chemischen Kenntniss der Mineralkörper, Fünfter Band, Rottmann Berlin, 32-36

Morimoto, N. and Koto, K. (1969) The crystal structure of orthoenstatite. Zeitschrift für Kristallographie: 129: 65-83.

Anastasiou, P. and Seifert, F. (1972) Solid solubility of Al2O3 in enstatite at high temperatures and 1-5 kb water pressure. Contributions to Mineralogy and Petrology: 34: 272-287.

Arima, M. and Onuma, K. (1977) The solubility of alumina in enstatite and the phase equilibria in the join MgSiO3-MgAl2SiO6 at 10-25 kbar. Contributions to Mineralogy and Petrology: 61: 251-265.

Hawthorne, F.C., and Ito, J. (1977) Synthesis and crystal structure refinement of transition-metal orthopyroxenes. I: orthoenstatite and (Mg,Mn,Co) orthopyroxene. Canadian Mineralogist: 15: 321-338.

Weidner, D.J., Wang, H., and Ito, J. (1978) Elasticity of orthoenstatite. Physics of the Earth and Planetary Interiors 17: 7-13.

Ralph, R.L. and Ghose, S. (1980) Enstatite, Mg2Si2O6: compressibility and crystal structure at 21 kbar (abs.). Eos: 61: 409.

Ohashi, Y. (1984) Polysynthetically-twinned structures of enstatite and wollastonite. Physics and Chemistry of Minerals: 10: 217-229.

Zeitschrift für Kristallographie (1986): 176: 159.

Duffy, T.S. and Vaughan, M.T. (1988) Elasticity of enstatite and its relationship to crystal structure. Journal of Geophysical Research: 93: 383-391.

Angel, R.J. and Hugh-Jones, D.A. (1994) Equation of state and thermodynamic properties of enstatite pyroxenes. Journal of Geophysical Research: 99: 19777-19783.

Hugh-Jones, D.A. and Angel, R.J. (1994) A compressional study of MgSiO3 orthoenstatite up to 8.5 GPa. American Mineralogist: 79: 405-410.

Yang, H. and Ghose, S. (1994) High-temperature single-crystal X-ray diffraction studies of the ortho-proto phase transition in enstatite, Mg2Si2O6 at 1360 K. Physics and Chemistry of Minerals: 22: 300-310.

Zhao, Y., Schiferl, D., and Shankland, T.J. (1995) A high P-T single-crystal X-ray diffraction study of thermoelasticity of MgSiO3 orthoenstatite. Pysics and Chemistry of Minerals: 22: 393-398.

Flesch, L.M., Li., B., and Liebermann, R.C. (1998) Sound velocities of polycrystalline MgSiO3-orthopyroxene to 10 GPa at room temperature. American Mineralogist: 83: 444-450.

Jackson, J.M., Sinogeikin, S.V., and Bass, J.D. (1999) Elasticity of MgSiO3 orthoenstatite. American Mineralogist: 84: 677-680.

Jackson, J.M., Palko, J., Sinogeikin, S.V., Bass, J.D., Andrault, D., and Zha, C. (2001) High-temperature single-crystal elasticity and thermal exansion of orthoenstatite. Eos (Fall Meeting Supplement), Abstract T31C-0853.

Angel, R.J. and Jackson, M.J. (2002) Elasticity and equation of state of orthoenstatite, MgSiO3. American Mineralogist: 87: 558-561.

Tarantino, S.C., Domeneghetti, M.C., Carpenter, M.A., Shaw, C.J.S., and Tazzoli, V. (2002a) Mixing properties of the enstatite-ferrosilite solid solution: I. A macroscopic perspective. European Journal of Mineralogy: 14: 525-536.

Tarantino, S.C., Boffa Ballaran, T., Carpenter, M.A., Domeneghetti, M.C., and Tazzoli, V. (2002b) Mixing properties of the enstatite-ferrosilite solid solution: II A microscopic perspective. Eurpean Journal of Mineralogy: 14: 537-547.

Lin, C.C. (2003) Pressure-induced metastable phase transition in orthoenstatite (MgSiO3) at room temperature: a Raman spectroscopic study. Journal of Solid State Chemistry: 174: 403-411.

Jackson, J.M., Sinogeikin, S.V., Carpenter, M.A., and Bass, J.D. (2004) Novel phase transition in orthoenstatite. American Mineralogist: 89: 239-245.

Kung, J., Li, B.S., Uchida, T., Wang, Y.B., Neuville, D., and Liebermann, R.C. (2004) In situ measurements of sound velocities and densities across the orthopyroxene - high-pressure clinopyroxene transition in MgSiO3 at high-pressure. Physics of the Earth and Planetary Interiors: 147: 27-44.

Nestola, F., Gatta, G.D., and Ballaran, T.B. (2006) The effect of Ca substitution on the elastic and structural behavior of orthoenstatite. American MIneralogist: 91: 809-815.