Grunerite Mineral Data

Grunerite Mineral Data +

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General Grunerite Information

Chemical Formula:

[ ]Fe++7Si8O22(OH)2

Composition:

Molecular Weight = 1,001.61 gm

Iron 39.03 % Fe 50.21 % FeO

Silicon 22.43 % Si 47.99 % SiO₂

Hydrogen 0.20 % H 1.80 % H₂O

Oxygen 38.34 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Fe²⁺₇(Si₈O₂₂)(OH)₂

IMA Status:

Valid Species (Pre-IMA) 1853

Locality:

Link to MinDat.org Location Data.

Name Origin:

Named for Louis Emmanuel Gruner (1809-1883), Swiss-French chemist who analyzed the mineral.

Synonym:

Amosite

ICSD 24590

PDF 44-1401

Grunerite Image

Images:

Grunerite

Comments: Olive green fibrous crystal aggregates of grunerite in rock matrix.
Location: Michigamme, Iron County, Michigan, USA. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Grunerite Crystallography

Axial Ratios:

a:b:c =0.5252:1:0.2925

Cell Dimensions:

a = 9.57, b = 18.22, c = 5.33, Z = 2; beta = 102.1° V = 908.72 Den(Calc)= 3.66

Crystal System:

Monoclinic - PrismaticH-M Symbol (2/m) Space Group: C 2/m

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

By Intensity(I/I_o): 8.33(1), 2.77(0.9), 3.07(0.8),

Crystal Structure:

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Finger L W , Mineralogical Society of America Special Paper , 2 (1969) p.95-100, The crystal structure and cation distribution of a grunerite, Locality: Wabush iron formation, Labrador, Canada

Physical Properties of Grunerite

Cleavage:

[110] Perfect, [???] Distinct

Color:

Ashen, Brown, Brownish green, Dark gray.

Density:

3.4 - 3.5, Average = 3.45

Diaphaniety:

Translucent to opaque

Fracture:

Sub Conchoidal - Fractures developed in brittle materials characterized by semi-curving surfaces.

Habit:

Columnar - Forms columns

Habit:

Fibrous - Crystals made up of fibers.

Habit:

Massive - Uniformly indistinguishable crystals forming large masses.

Hardness:

5-6 - Between Apatite and Orthoclase

Luminescence:

Non-fluorescent.

Luster:

Vitreous - Pearly

Streak:

colorless

Optical Properties of Grunerite

Gladstone-Dale:

CI meas= -0.004 (Superior) - where the CI = (1-KPDmeas/KC)
CI calc= 0.054 (Good) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.1896,KPDmeas= 0.2011,KC= 0.2003

Optical Data:

Biaxial (-), a=1.663-1.686, b=1.68-1.709, g=1.696-1.729, bire=0.0330-0.0430, 2V(Calc)=84-86, 2V(Meas)=90-70. Dispersion r > v.

Pleochroism (x):

colorless, colorless, or pale yellow.

Pleochroism (y):

colorless, pale yellow, or yellowish gray.

Pleochroism (z):

colorless, pale green, pale yellow, or pale greenish yellow.

Calculated Properties of Grunerite

Electron Density:

r_electron=3.36 gm/cc
note: r_Grunerite=3.45 gm/cc.

Fermion Index

Fermion Index = 0.01893
Boson Index = 0.98107

Photoelectric:

PE_Grunerite= 12.52 barns/electron
U=PE_Grunerite x r_electron= 42.08 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Grunerite is Not Radioactive

Grunerite Classification

Dana Class:

66.1.1.3 (66)Inosilicate Double-Width Unbranched Chains, W=2

(66.1)Dana Type

(66.1.1)Group 1, the Mg-Fe-Mn-Li amphiboles (Monoclinic)

66.1.1.1 Magnesiocummingtonite (Mg,Fe)7Si8O22(OH)2 C 2/m 2/m

66.1.1.2 Cummingtonite []Mg7Si8O22(OH)2 C 2/m 2/m

66.1.1.3 Grunerite []Fe7Si8O22(OH)2 C 2/m 2/m

66.1.1.3b Permanganogrunerite! []Mn4(Fe)3(Si8O22)(OH)2 C 2/m 2/m

66.1.1.4 Manganocummingtonite Na(Na,Mn)2(Mg4,Fe)5Si8O22(OH)2 C 2/m 2/m

66.1.1.5 Manganogrunerite []Mn2Fe5Si8O22(OH) C 2/m 2/m

66.1.1.6 Magnesioclinoholmquistite? Li2(Mg,Fe)3Al2Si8O22(OH)2 C 2/m 2/m

66.1.1.7 Clinoholmquistite? [](Li2Mg3Al2)Si8O22(OH)2 C 2/m 2/m

66.1.1.8 Clinoferroholmquistite [](Li2Fe3Al2)Si8O22(OH)2 C 2/m 2/m

66.1.1.8a Ferri-clinoholmquistite! []Li2Mg3(Fe3)2(Si8O22)(OH)2 C 2/m 2/m

66.1.1.8b Ferri-clinoferroholmquistite! []Li2(Fe2Fe3)Si8O22(OH)2 C 2/m 2/m

66.1.1.9 Sodic-ferripedrizite! Na(LiNa)(Fe2Mg2Li)Si8O22(OH,F)2 C 2/m 2/m

66.1.1.9a Ferripedrizite! NaLi2(Fe2Mg2Li)Si8O22(OH)2 C 2/m 2/m

66.1.1.9b Sodic-ferri-ferropedrizite! NaLi2(Fe2Fe3)Si8O22(OH)2 C 2/m 2/m

66.1.1.9c Fluoro-sodic-pedrizite! NaLi2(Mg2Al2Li)S5Si8O22F2 C 2/m 2/m

Strunz Class:

VIII/F.07-30 VIII - Silicates

VIII/F - Inosilicates (chain and band) double chains [Si4O11]6- , Mg-Fe-Mn-Amphiboles

VIII/F.07 - Amphibole group, Magnesiocummingtonite - Ferroclinoholmquistite series

VIII/F.07-10 Magnesiocummingtonite (Mg,Fe)7Si8O22(OH)2 C 2/m 2/m

VIII/F.07-20 Cummingtonite []Mg7Si8O22(OH)2 C 2/m 2/m

VIII/F.07-30 Grunerite []Fe7Si8O22(OH)2 C 2/m 2/m

VIII/F.07-40 Manganocummingtonite Na(Na,Mn)2(Mg4,Fe)5Si8O22(OH)2 C 2/m 2/m

VIII/F.07-50 Manganogrunerite []Mn2Fe5Si8O22(OH) C 2/m 2/m

VIII/F.07-55 Permanganogrunerite! []Mn4(Fe)3(Si8O22)(OH)2 C 2/m 2/m

VIII/F.07-60 Magnesioclinoholmquistite? Li2(Mg,Fe)3Al2Si8O22(OH)2 C 2/m 2/m

VIII/F.07-70 Clinoholmquistite? [](Li2Mg3Al2)Si8O22(OH)2 C 2/m 2/m

VIII/F.07-80 Clinoferroholmquistite [](Li2Fe3Al2)Si8O22(OH)2 C 2/m 2/m

VIII/F.07-90 Ferri-clinoferroholmquistite! []Li2(Fe2Fe3)Si8O22(OH)2 C 2/m 2/m

Other Grunerite Information

References:

NAME( Dana8) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Heinrich65)

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Grunerite

[ ]Fe++7Si8O22(OH)2
Dana No: 66.1.1.3 Strunz No: VIII/F.07-30
Locality:

Notes: