Ferrosilite Mineral Data

Ferrosilite Mineral Data +

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General Ferrosilite Information

Chemical Formula:

(Fe++,Mg)2Si2O6

Composition:

Molecular Weight = 232.32 gm

Magnesium 10.46 % Mg 17.35 % MgO

Iron 24.04 % Fe 30.93 % FeO

Silicon 24.18 % Si 51.73 % SiO₂

Oxygen 41.32 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Fe²⁺MgSi₂O₆

Environment:

Found in basic and ultrabasic igneous rocks.

IMA Status:

Valid Species (Pre-IMA) 1935

Locality:

Unspecified locality in Russia. Link to MinDat.org Location Data.

Name Origin:

Named for its composition (Ferrous Silicate).

Synonym:

ICSD 17055

Orthoferrosilite

PDF 29-721

Ferrosilite Image

Images:

Ferrosilite

Comments: Transparent, brown prismatic blades of ferrosilite crystals on matrix.
Location: Summit Rock, Diamond Lake, Douglas County, Oregon, USA. Scale: Not Given.
© Lou Perloff / Photo Atlas of Minerals

Ferrosilite Crystallography

Axial Ratios:

a:b:c =2.0288:1:0.5768

Cell Dimensions:

a = 18.418, b = 9.078, c = 5.237, Z = 8; V = 875.62 Den(Calc)= 3.52

Crystal System:

Orthorhombic - DipyramidalH-M Symbol (2/m 2/m 2/m) Space Group: P bca

$Help on X Ray Diffraction:$ X Ray Diffraction:

By Intensity(I/I_o): 2.91(1), 4.61(0.9), 3(0.8),3.23(0.7), 2.59(0.4), 2.52(0.3), 6.46(0.3), 1.781(0.2),

Crystal Structure:

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Burnham C W , Ohashi Y , Hafner S S , Virgo D , American Mineralogist , 56 (1971) p.850-876, Cation distribution and atomic thermal vibrations in an iron-rich orthopyroxene

View Additional jPOWD Structure files for Ferrosilite
[1] [10] [11] [12] [13] [14] [15] [2] [3] [4] [5] [6] [7] [8] [9]

Physical Properties of Ferrosilite

Cleavage:

[210] Good, [100] Parting

Color:

Colorless, Green, Dark brown, Nearly black.

Density:

3.88 - 4.02, Average = 3.95

Diaphaniety:

Translucent to Opaque

Habit:

Anhedral Grains - Granular minerals without the expression of crystal shapes

Hardness:

5-6 - Between Apatite and Orthoclase

Luster:

Vitreous (Glassy)

Streak:

pale brownish gray

Optical Properties of Ferrosilite

Gladstone-Dale:

CI meas= 0.056 (Good) - where the CI = (1-KPDmeas/KC)
CI calc= -0.059 (Fair) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2123,KPDmeas= 0.1892,KC= 0.2004

Optical Data:

Biaxial (+), a=1.71-1.767, b=1.723-1.77, g=1.726-1.788, bire=0.0160-0.0210

Pleochroism (x):

pinkish brown.

Pleochroism (z):

greenish brown.

Calculated Properties of Ferrosilite

Electron Density:

r_electron=3.88 gm/cc
note: r_Ferrosilite=3.95 gm/cc.

Fermion Index

Fermion Index = 0.02704
Boson Index = 0.97296

Photoelectric:

PE_Ferrosilite= 8.29 barns/electron
U=PE_Ferrosilite x r_electron= 32.13 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Ferrosilite is Not Radioactive

Ferrosilite Classification

Dana Class:

65.1.2.2 (65)Inosilicate Single-Width Unbranched Chains, W=1

(65.1)with chains P=2

(65.1.2)Orthopyroxenes

65.1.2.1 Enstatite Mg2Si2O6 P bca 2/m 2/m 2/m

65.1.2.2 Ferrosilite (Fe,Mg)2Si2O6 P bca 2/m 2/m 2/m

65.1.2.3 Donpeacorite (Mn,Mg)MgSi2O6 P bca 2/m 2/m 2/m

Strunz Class:

VIII/F.02-20 VIII - Silicates

VIII/F - Inosilicates (chain and band) double chains [Si2O6]4-

VIII/F.02 - Pyroxene group, Orthopyroxene

VIII/F.02-10 Enstatite Mg2Si2O6 P bca 2/m 2/m 2/m

VIII/F.02-20 Ferrosilite (Fe,Mg)2Si2O6 P bca 2/m 2/m 2/m

VIII/F.02-30 Donpeacorite (Mn,Mg)MgSi2O6 P bca 2/m 2/m 2/m

VIII/F.02-40 Nchwaningite Mn2SiO3(OH)2·(H2O) P ca2₁ mm2

Other Ferrosilite Information

References:

NAME( Dana8) PHYS. PROP.(Dana8) OPTIC PROP.(Dana8)

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Ferrosilite

(Fe++,Mg)2Si2O6
Dana No: 65.1.2.2 Strunz No: VIII/F.02-20
Locality:

Notes: