Jimthompsonite Mineral Data

General Jimthompsonite Information

Chemical Formula:

(Mg,Fe++)5Si6O16(OH)2

Composition:

Molecular Weight = 619.47 gm

Magnesium 14.71 % Mg 24.40 % MgO

Iron 11.27 % Fe 14.50 % FeO

Silicon 27.20 % Si 58.20 % SiO₂

Hydrogen 0.33 % H 2.91 % H₂O

Oxygen 46.49 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Mg_3.75Fe²⁺_1.25Si₆O₁₆(OH)₂

Environment:

In the black wallrock between chlorite and actinolite zones of a metamorphosed ultramafic body.

IMA Status:

Approved IMA 1978

Locality:

In the Carleton talc quarry, near Chester, Windsor Co., Vermont, USA. Link to MinDat.org Location Data.

Name Origin:

Named for James Burleigh Thompson, Jr. (1921- ), eminent petrologist of Harvard University, Cambridge, Massachusetts, USA.

Name Pronunciation:

Jimthompsonite + Pronunciation

Synonym:

ICSD 100657

PDF 31-638

Jimthompsonite Image

Images:

Clinojimthompsonite Jimthompsonite

Comments: Pale green to white glassy crystalline fibrous clinojimthompsonite intergrown with jimthompsonite.
Location: Chester, Windsor County, Vermont, USA. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Jimthompsonite Crystallography

Axial Ratios:

a:b:c =0.684:1:0.1945

Cell Dimensions:

a = 18.626, b = 27.23, c = 5.297, Z = 8; V = 2,686.56 Den(Calc)= 3.06

Crystal System:

Orthorhombic - Dipyramidal H-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): 8.812(1), 13.6(0.57), 3.092(0.53),

Physical Properties of Jimthompsonite

Cleavage:

{210} Perfect

Color:

Colorless, Pink brown.

Density:

3.03

Diaphaneity:

Transparent

Hardness:

2-2.5 - Gypsum-Finger Nail

Luster:

Silky - Pearly

Streak:

white

Optical Properties of Jimthompsonite

Gladstone-Dale:

CI meas= 0.009 (Superior) - where the CI = (1-KPDmeas/KC)
CI calc= 0.019 (Excellent) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2031,KPDmeas= 0.2051,KC= 0.207
Ncalc = 1.63

Optical Data:

Biaxial (-), a=1.605, b=1.626, g=1.633, bire=0.0280, 2V(Calc)=58, 2V(Meas)=62.

Calculated Properties of Jimthompsonite

Electron Density:

Bulk Density (Electron Density)=3.01 gm/cc
note: Specific Gravity of Jimthompsonite =3.03 gm/cc.

Fermion Index:

Fermion Index = 0.03
Boson Index = 0.97

Photoelectric:

PE_{Jimthompsonite}= 4.68 barns/electron
U=PE_{Jimthompsonite} x rElectron Density= 14.09 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Jimthompsonite is Not Radioactive

Jimthompsonite Classification

Dana Class:

67.01.01.01 (67)Inosilicate Unbranched Chains with W>2

(67.01)with W=3

(67.01.01)Jimthompsonite group

67.01.01.01 Jimthompsonite (Mg,Fe)5Si6O16(OH)2 P bca 2/m 2/m 2/m

67.01.01.02 Clinojimthompsonite (Mg,Fe)5Si6O16(OH)2 C 2/c 2/m

Strunz Class:

09.DF.05 09 - SILICATES (Germanates)

09.D - Inosilicates* Structural terminology according to Liebau (1985)

09.DF -Inosilicates with 2-periodic multiple chains

09.DF.05 Chesterite (Mg,Fe)17Si20O54(OH)6 A21ma mm2

09.DF.05 Clinojimthompsonite (Mg,Fe)5Si6O16(OH)2 C 2/c 2/m

09.DF.05 Jimthompsonite (Mg,Fe)5Si6O16(OH)2 P bca 2/m 2/m 2/m

Other Jimthompsonite Information

References:

NAME( AntBidBlaNic2) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Enc. of Minerals,2nd ed.,1990)

See Also:

Links to other databases for Jimthompsonite :
1 - Am. Min. Crystal Structure Database
2 - Athena
3 - EUROmin Project
4 - Ecole des Mines de Paris
5 - GeoScienceWorld
6 - Google Images
7 - Google Scholar
8 - Handbook of Mineralogy (MinSocAm)
9 - Handbook of Mineralogy (UofA)
10 - MinDAT
11 - Mineralienatlas (Deutsch)
12 - Online Mineral Museum
13 - QUT Mineral Atlas
14 - Ruff.Info
15 - WWW-MINCRYST

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Jimthompsonite

(Mg,Fe++)5Si6O16(OH)2
Dana No: 67.01.01.01 Strunz No: 09.DF.05
Locality:

Notes:

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