Franciscanite-III Mineral Data
General Franciscanite-III Information
Chemical Formula:
Mn++6V+++++2Si2(O,OH)14
Composition:
Molecular Weight = 713.69 gm
Manganese 46.19 % Mn 59.64 % MnO
Vanadium 14.28 % V 25.48 % V2 O5
Silicon 7.87 % Si 16.84 % SiO2
Hydrogen 0.28 % H 2.52 % H2 O
Oxygen 31.39 % O
______ ______
100.00 % 104.48 % = TOTAL OXIDE
Empirical Formula:
Mn2+ 6 V5+ 2 Si2 O12 (OH)2
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 age Franciscan Formation.
Name Pronunciation:
Franciscanite-III + Pronunciation
Franciscanite-III Image
Images:
Franciscanite-III
Comments: Dark reddish brown large franciscanite grains to 1.5cm in tan-colored gageite matrix.
Location: Pennsylvania mine, Santa Clara Co., California, USA.
Scale: 5.5 x 4 x 3cm.
© Tom Loomis / Dakota Matrix
Franciscanite-III Crystallography
Axial Ratios:
a:c = 1:0.58959
Cell Dimensions:
a = 8.148, c = 4.804, Z = 1; V = 276.21 Den(Calc)= 4.29
Crystal System:
Trigonal - Pyramidal H-M Symbol (3) Space Group: P 3
X Ray Diffraction:
By Intensity(I/Io ): 2.331(1), 2.844(0.9), 3.105(0.9),
Physical Properties of Franciscanite-III
Color:
Red.
Density:
4.1
Diaphaneity:
Transparent to Translucent
Hardness:
4 - Fluorite
Luster:
Vitreous (Glassy)
Optical Properties of Franciscanite-III
Gladstone-Dale:
CI meas = 0.146 (Poor) - where the CI = (1-KPDmeas /KC ) CI calc = 0.184 (Poor) - where the CI = (1-KPDcalc /KC )
KPDcalc = 0.2022,KPDmeas = 0.2116,KC = 0.2477 Ncalc = 2.02 - 2.06
Optical Data:
Uniaxial (+), w=1.859, e=1.876, bire=0.0170.
Calculated Properties of Franciscanite-III
Electron Density:
Bulk Density (Electron Density)=3.88 gm/cc note: Specific Gravity of Franciscanite-III =4.10 gm/cc.
Fermion Index:
Fermion Index = 0.0041834865 Boson Index = 0.9958165135
Photoelectric:
PEFranciscanite-III = 15.10 barns/electronU=PEFranciscanite-III x r Electron Density= 58.64 barns/cc.
Radioactivity:
GRapi = 0 (Gamma Ray American Petroleum Institute Units) Franciscanite-III is Not Radioactive
Franciscanite-III Classification
Dana Class:
07.03.01.02 (07) Multiple Oxides
(07.03) with 2+ and higher charged cations
(07.03.01) containing Mn (Hexagonal, P3)
07.03.01.01 Welinite-III Mn6(W,Mg)2Si2(O,OH)14 P 3 3
07.03.01.02 Franciscanite-III Mn6V2Si2(O,OH)14 P 3 3
07.03.01.03 Orebroite-III Mn6(Fe,Sb)2Si2(O,OH)14 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-III 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-III :
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-III
Mn++6V+++++2Si2(O,OH)14
Dana No: 07.03.01.02 Strunz No: 09.AF.07.5
Locality:
Notes:
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