Johnsomervilleite Mineral Data

General Johnsomervilleite Information

Chemical Formula:

Na2Ca(Mg,Fe++,Mn)7(PO4)6

Composition:

Molecular Weight = 955.37 gm

Sodium 3.37 % Na 4.54 % Na₂O

Calcium 4.61 % Ca 6.46 % CaO

Magnesium 7.89 % Mg 13.08 % MgO

Manganese 4.03 % Mn 5.20 % MnO

Iron 20.46 % Fe 26.32 % FeO

Phosphorus 19.45 % P 44.57 % P₂O₅

Oxygen 40.19 % O

______ ______

100.00 % 100.17 % = TOTAL OXIDE

Empirical Formula:

Na_1.4Ca_1.1Fe²⁺_3.5Mg_3.1Mn²⁺_0.7(PO₄)₆

Environment:

Accessory mineral in podiform metamorphic segregations in kyanite-sillimanite-grade gneiss.

IMA Status:

Approved IMA 1980

Locality:

Glen Cosaidh, Loch Quoich,, Inverness-shire, Scotland. Link to MinDat.org Location Data.

Name Origin:

Named for John M. Somerville (1908-1978), who collected the first specimen.

Name Pronunciation:

Johnsomervilleite + Pronunciation

Johnsomervilleite Image

Images:

Johnsomervilleite

Comments: Dark brownish johnsomervilleite.
Location: Sapucaia Mine, Conselheiro Pena district, GalilÃ©ia, Governador Valadares, Rio Doce, Minas Gerais, Southeast Region, Brazil. Scale: Picture size 5 mm.
© Thomas Witzke / Abraxas-Verlag

Johnsomervilleite Crystallography

Axial Ratios:

a:c = 1:2.84999

Cell Dimensions:

a = 15, c = 42.75, Z = 18; V = 8,330.08 Den(Calc)= 3.43

Crystal System:

Trigonal - Rhombohedral H-M Symbol ( 3) Space Group: R 3

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

By Intensity(I/I_o): 2.764(1), 3.55(0.7), 3.7(0.7),

Physical Properties of Johnsomervilleite

Cleavage:

{0001} Perfect

Color:

Dark brown, Blackish gray.

Density:

3.35

Diaphaneity:

Transparent to Translucent

Fracture:

Brittle - Splintery - Brittle fracture leaving splintery fragments.

Habit:

Colloform - Forming from a gel or colloidal mass.

Habit:

Dendritic - Branching "tree-like" growths of great complexity (e.g. pyrolusite).

Habit:

Granular - Generally occurs as anhedral to subhedral crystals in matrix.

Hardness:

4.5 - Between Fluorite and Apatite

Luster:

Vitreous (Glassy)

Streak:

light brown

Optical Properties of Johnsomervilleite

Gladstone-Dale:

CI meas= -0.031 (Excellent) - where the CI = (1-KPDmeas/KC)
CI calc= -0.007 (Superior) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.191,KPDmeas= 0.1955,KC= 0.1896
Ncalc = 1.64 - 1.65

Optical Data:

Uniaxial (+/-), a=1.655, b=1.655, bire=0.0000.

Calculated Properties of Johnsomervilleite

Electron Density:

Bulk Density (Electron Density)=3.34 gm/cc
note: Specific Gravity of Johnsomervilleite =3.43 gm/cc.

Fermion Index:

Fermion Index = 0.01
Boson Index = 0.99

Photoelectric:

PE_{Johnsomervilleite}= 8.87 barns/electron
U=PE_{Johnsomervilleite} x rElectron Density= 29.62 barns/cc.

Radioactivity:

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

Johnsomervilleite Classification

Dana Class:

38.02.05.02 (38)Anhydrous Phosphates, etc

(38.02)(A+ B++)5 (XO4)3

(38.02.05)Fillowite Group

38.02.05.01 Fillowite Na2Ca(Mn,Fe)7(PO4)6 R 3 3

38.02.05.02 Johnsomervilleite Na2Ca(Mg,Fe,Mn)7(PO4)6 R 3 3

38.02.05.03 Chladniite Na2Ca(Mg,Fe)7(PO4)6 R 3 3

38.02.05.04 Galileiite! NaFe4(PO4)3 R 3 3

38.02.05.05 Xenophyllite! Na4Fe7(PO4)6 P1 or P1 Tri

38.02.05.06 Stornesite-(Y)! (Y,Ca)[]2Na6(Ca,Na)8(Mg,Fe)43(PO4)36 R 3 3

Strunz Class:

08.AC.50 08 - PHOSPHATES, ARSENATES, VANADATES

08.A - Phosphates, etc. without additional anions, without H2O

08.AC -With medium-sized and large cations

08.AC.50 Fillowite Na2Ca(Mn,Fe)7(PO4)6 R 3 3

08.AC.50 Chladniite Na2Ca(Mg,Fe)7(PO4)6 R 3 3

08.AC.50 Johnsomervilleite Na2Ca(Mg,Fe,Mn)7(PO4)6 R 3 3

08.AC.50 Galileiite! NaFe4(PO4)3 R 3 3

08.AC.50 Stornesite-(Y)! (Y,Ca)[]2Na6(Ca,Na)8(Mg,Fe)43(PO4)36 R 3 3

08.AC.50 Xenophyllite! Na4Fe7(PO4)6 P1 or P1 Tri

Other Johnsomervilleite Information

References:

NAME( AntBidBlaNic4) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Enc. of Minerals,2nd ed.,1990)

See Also:

Links to other databases for Johnsomervilleite :
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

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Print or Cut-and-Paste your Johnsomervilleite Specimen Label here :

Johnsomervilleite

Na2Ca(Mg,Fe++,Mn)7(PO4)6
Dana No: 38.02.05.02 Strunz No: 08.AC.50
Locality:

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