Franciscanite-VIII Mineral Data

General Franciscanite-VIII Information

Chemical Formula:

Mn++3(V+++++,[ ])1-x(SiO4)(O,OH)3(x=0.5)

Composition:

Molecular Weight = 331.88 gm

Manganese 49.66 % Mn 64.12 % MnO

Vanadium 7.67 % V 13.70 % V₂O₅

Silicon 8.46 % Si 18.10 % SiO₂

Hydrogen 0.46 % H 4.07 % H₂O

Oxygen 33.75 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Mn²⁺₃V⁵⁺_0.5(SiO₄)O_1.5(OH)_1.5

Environment:

Irregular segregations within a sheared sonolite-bearing assemblage in chert.

IMA Status:

Approved IMA 1986

Locality:

Pennsylvania mine, SW side of San Antonio Valley, 4 miles ENE of Mount Halilton, Santa Clara Co. California. Link to MinDat.org Location Data.

Name Origin:

Named after the Miocene-aged Franciscan Formation in California, USA..

Name Pronunciation:

Franciscanite-VIII + Pronunciation

Franciscanite-VIII Crystallography

Axial Ratios:

a:c = 1:0.58959

Cell Dimensions:

a = 8.148, c = 4.804, Z = 2; V = 276.21 Den(Calc)= 3.99

Crystal System:

Trigonal - Pyramidal H-M Symbol (3) Space Group: P 3

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

By Intensity(I/I_o): 2.331(1), 3.105(0.9), 2.844(0.9),1.785(0.7), 1.538(0.5), 2.668(0.4), 3.97(0.3),

Physical Properties of Franciscanite-VIII

Color:

Red, Reddish brown.

Density:

4.1

Diaphaneity:

Transparent to Translucent

Fracture:

Uneven - Flat surfaces (not cleavage) fractured in an uneven pattern.

Habit:

Irregular Grains - Occurs as splotchy, anhedral crystals forming inclusions in other minerals or rocks.

Hardness:

4 - Fluorite

Luster:

Vitreous (Glassy)

Magnetism:

Weakly magnetic

Optical Properties of Franciscanite-VIII

Dichroism (e):

wine red or wine red.

Dichroism (w):

dark red or nearly black.

Gladstone-Dale:

CI meas= 0.056 (Good) - where the CI = (1-KPDmeas/KC)
CI calc= 0.03 (Excellent) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2176,KPDmeas= 0.2118,KC= 0.2244
Ncalc = 1.9 - 1.92

Optical Data:

Uniaxial (+), w=1.856-1.859, e=1.876-1.882, bire=0.0200-0.0230.

Calculated Properties of Franciscanite-VIII

Electron Density:

Bulk Density (Electron Density)=3.80 gm/cc
note: Specific Gravity of Franciscanite-VIII =3.99 gm/cc.

Fermion Index:

Fermion Index = 0.0043065645
Boson Index = 0.9956934355

Photoelectric:

PE_{Franciscanite-VIII}= 14.70 barns/electron
U=PE_{Franciscanite-VIII} x rElectron Density= 55.84 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Franciscanite-VIII is Not Radioactive

Franciscanite-VIII Classification

Dana Class:

52.04.01.04 (52)Nesosilicate Insular SiO4 Groups and O, OH, F, and H2O

(52.04)with cations in [6] and/or > [6] coordination

(52.04.01)Welinite group

52.04.01.01 Orebroite-VIII Mn3(Sb,Fe)SiO4(O,OH)3 P 3 3

52.04.01.02 Welinite-VIII (Mn,Mg)3(W,Mn)1-x(SiO4)(O,OH)3(x=1/3) P 3 3

52.04.01.03 Kittatinnyite Ca2Mn2MnSi2O8(OH)4•9(H2O) P 6₃/mmc 6/m 2/m 2/m

52.04.01.04 Franciscanite-VIII Mn3(V,[])1-x(SiO4)(O,OH)3(x=0.5) P 3 3

Strunz Class:

09.AF.07.5 09 - SILICATES (Germanates)

09.A - Nesosilicates

09.AF -Nesosilicates with additional anions;

09.AF.07.5 Franciscanite-III Mn6V2Si2(O,OH)14 P 3 3

09.AF.07.5 Franciscanite-VIII Mn3(V,[])1-x(SiO4)(O,OH)3(x=0.5) P 3 3

09.AF.07.5 Orebroite-III Mn6(Fe,Sb)2Si2(O,OH)14 P 3 3

09.AF.07.5 Welinite-III Mn6(W,Mg)2Si2(O,OH)14 P 3 3

09.AF.07.5 Welinite-VIII (Mn,Mg)3(W,Mn)1-x(SiO4)(O,OH)3(x=1/3) P 3 3

Other Franciscanite-VIII Information

References:

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

See Also:

Links to other databases for Franciscanite-VIII :
1 - Am. Min. Crystal Structure Database
2 - Athena
3 - GeoScienceWorld
4 - Google Images
5 - Google Scholar
6 - MinDAT
7 - Mineralienatlas (Deutsch)
8 - Online Mineral Museum
9 - QUT Mineral Atlas
10 - Ruff.Info

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Franciscanite-VIII

Mn++3(V+++++,[ ])1-x(SiO4)(O,OH)3(x=0.5)
Dana No: 52.04.01.04 Strunz No: 09.AF.07.5
Locality:

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