Johnsomervilleite Mineral Data

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.

Johnsomervilleite Image

Images:

Johnsomervilleite

Comments: Dark brownish johnsomervilleite.
Location: Sapucaia Mine, Conselheiro Pena district, Galil?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 - RhombohedralH-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

Diaphaniety:

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

Optical Data:

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

Calculated Properties of Johnsomervilleite

Electron Density:

r_electron=3.34 gm/cc
note: r_{Johnsomervilleite}=3.43 gm/cc.

Fermion Index

Fermion Index = 0.01247
Boson Index = 0.98753

Photoelectric:

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

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Johnsomervilleite is Not Radioactive

Johnsomervilleite Classification

Dana Class:

38.2.5.2 (38)Anhydrous Phosphates, etc

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

(38.2.5)Dana Group

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

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

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

38.2.5.4 Galileiite! NaFe4(PO4)3 R 3 3

Strunz Class:

VII/A.08-10 VII - Phosphates, Arsenates and Vanadates

VII/A - Waterfree phosphates [PO4]3- without unfamiliar anions, cations of medium and big size: Mg, Mn,Fe, Cu, Zn, and Ca, Na

VII/A.08 - Chladniite - Berzeliite - Palenzonaite series

VII/A.08-03 Galileiite! NaFe4(PO4)3 R 3 3

VII/A.08-05 Chladniite Na2Ca(Mg,Fe)7(PO4)6 R 3 3

VII/A.08-10 Johnsomervilleite Na2Ca(Mg,Fe,Mn)7(PO4)6 R 3 3

VII/A.08-20 Fillowite Na2Ca(Mn,Fe)7(PO4)6 R 3 3

VII/A.08-30 Berzeliite (Ca,Na)3(Mg,Mn)2(AsO4)3 I a3d 4/m 3 2/m

VII/A.08-40 Manganberzeliite (Ca,Na)3(Mn,Mg)2(AsO4)3 I a3d 4/m 3 2/m

VII/A.08-45 Schaferite! NaCa2Mg2(VO4)3 I a3d 4/m 3 2/m

VII/A.08-50 Palenzonaite (Ca,Na)3Mn(V,As,Si)3O12 I a3d 4/m 3 2/m

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 -Google Images 5 -Google Scholar 6 -Handbook of Mineralogy (UofA) 7 -MinDAT 8 -MinMax(Deutsch) 9 -MinMax(English) 10 -Mineralienatlas (Deutsch) 11 -QUT Mineral Atlas 12 -École des Mines de Paris

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Johnsomervilleite

Na2Ca(Mg,Fe++,Mn)7(PO4)6
Dana No: 38.2.5.2 Strunz No: VII/A.08-10
Locality:

Notes: