Franciscanite
A valid IMA mineral species
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About Franciscanite
Formula:
Mn2+6(V5+,◻)2(SiO4)2(O,OH)6
Colour:
Brown red, red
Lustre:
Vitreous
Hardness:
4
Specific Gravity:
4.1
Crystal System:
Trigonal
Member of:
Name:
Named after the Miocene age Franciscan Formation, where the mineral was found.
This page provides mineralogical data about Franciscanite.
Unique Identifiers
Mindat ID:
1590
Long-form identifier:
mindat:1:1:1590:1
Similar Names
| Franciscanite-III | Mn62+V25+Si2(O,OH)14 |
IMA Classification of Franciscanite
Approved
IMA Formula:
Mn2+6(V5+◻)(SiO4)2O3(OH)3
Approval year:
1985
First published:
1986
Classification of Franciscanite
9.AF.75
9 : SILICATES (Germanates)
A : Nesosilicates
F : Nesosilicates with additional anions; cations in [4], [5] and/or only [6] coordination
9 : SILICATES (Germanates)
A : Nesosilicates
F : Nesosilicates with additional anions; cations in [4], [5] and/or only [6] coordination
52.4.1.4
52 : NESOSILICATES Insular SiO4 Groups and O,OH,F,H2O
4 : Insular SiO4 Groups and O, OH, F, and H2O with cations in [6] and/or >[6] coordination
52 : NESOSILICATES Insular SiO4 Groups and O,OH,F,H2O
4 : Insular SiO4 Groups and O, OH, F, and H2O with cations in [6] and/or >[6] coordination
17.7.2
17 : Silicates Containing other Anions
7 : Silicates with vanadate, arsenate or antimonate
17 : Silicates Containing other Anions
7 : Silicates with vanadate, arsenate or antimonate
Mineral Symbols
As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.
| Symbol | Source | Reference for Standard |
|---|---|---|
| Fcc | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
Physical Properties of Franciscanite
Vitreous
Transparency:
Transparent
Colour:
Brown red, red
Comment:
Cherry-red when fresh, darkening with time.
Streak:
Brownish red
Hardness:
4 on Mohs scale
Cleavage:
None Observed
Fracture:
Irregular/Uneven
Density:
4.1(3) g/cm3 (Measured) 3.97 g/cm3 (Calculated)
Optical Data of Franciscanite
Type:
Uniaxial (+)
RI values:
nω = 1.856(3) nε = 1.882
Max. Birefringence:
δ = 0.026
Based on recorded range of RI values above.
Based on recorded range of RI values above.
Interference Colours:
The colours simulate birefringence patterns seen in thin section under crossed polars. They do not take into account mineral colouration or opacity.
Michel-Levy Bar The default colours simulate the birefringence range for a 30 µm thin-section thickness. Adjust the slider to simulate a different thickness.
Grain Simulation You can rotate the grain simulation to show how this range might look as you rotated a sample under crossed polars. Each grain retains its interference colour (retardation) while its brightness falls to black at extinction and reaches a maximum between extinction positions.
The colours simulate birefringence patterns seen in thin section under crossed polars. They do not take into account mineral colouration or opacity.
Michel-Levy Bar The default colours simulate the birefringence range for a 30 µm thin-section thickness. Adjust the slider to simulate a different thickness.
Grain Simulation You can rotate the grain simulation to show how this range might look as you rotated a sample under crossed polars. Each grain retains its interference colour (retardation) while its brightness falls to black at extinction and reaches a maximum between extinction positions.
Surface Relief:
Moderate
Pleochroism:
Strong
Comments:
O = wine-red; E = dark red to nearly black
Comments:
Absorption is intense, E >> O.
Chemistry of Franciscanite
Mindat Formula:
Mn2+6(V5+,◻)2(SiO4)2(O,OH)6
Element Weights:
Crystallography of Franciscanite
Crystal System:
Trigonal
Class (H-M):
3 - Pyramidal
Space Group:
P3
Cell Parameters:
a = 8.1518(3) Å, c = 4.8091(2) Å
Ratio:
a:c = 1 : 0.59
Unit Cell V:
276.76 ų (Calculated from Unit Cell)
Z:
2
Crystal Structure
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Data courtesy of the American Mineralogist Crystal Structure Database. Click on an AMCSD ID to view structure
| ID | Species | Reference | Link | Year | Locality | Pressure (GPa) | Temp (K) |
|---|---|---|---|---|---|---|---|
| 0014805 | Franciscanite | Pertlik F (1986) The crystal structure of franciscanite, Mn3(Vx_1-x)(SiO4)(O,OH)3,(x ~ 0.5) California, USA Neues Jahrbuch fur Mineralogie, Monatshefte 1986 493-499 | 1986 | Franciscan Complex, Pennsylvania mine, Santa Clara County, | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 2.331 Å | (100) |
| 3.105 Å | (90) |
| 2.844 Å | (90) |
| 1.785 Å | (70) |
| 1.538 Å | (50) |
| 2.668 Å | (40) |
| 3.97 Å | (30) |
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| High-? alteration and/or metamorphism | |
| 32 : Ba/Mn/Pb/Zn deposits, including metamorphic deposits |
Type Occurrence of Franciscanite
General Appearance of Type Material:
Glassy, irregular grains, up to 1.0 mm in diameter.
Place of Conservation of Type Material:
National Museum of Natural History, Washington, D.C., USA, 163041.
Geological Setting of Type Material:
Segregations in a sheared sonolite-hausmannite-gageite assemblage in chert.
Associated Minerals at Type Locality:
Synonyms of Franciscanite
Other Language Names for Franciscanite
Relationship of Franciscanite to other Species
Member of:
Other Members of Welinite Group:
| Barwoodite | Mn2+6Nb5+(SiO4)2O3(OH)3 | Trig. 3 : P3 |
| Örebroite | Mn2+3(Sb5+,Fe3+)(SiO4)(O,OH)3 | Trig. 3 : P3 |
| Scorticoite | Mn6(Sb,◻)Σ2(SiO4)2O3(OH)3 | Trig. 3 : P3 |
| Welinite | Mn2+6(W6+,Mg)2(SiO4)2(O,OH)6 | Trig. 3 : P3 |
Related Minerals - Strunz-mindat Grouping
| 9.AF. | Chegemite | Ca7(SiO4)3(OH)2 |
| 9.AF. | Jingwenite-(Y) | YAlV4+(SiO4)O2(OH)2 |
| 9.AF. | Barwoodite | Mn2+6Nb5+(SiO4)2O3(OH)3 |
| 9.AF.05 | Sillimanite | Al2(SiO4)O |
| 9.AF.05 | 'Xenolite' | Al10Si8O31 |
| 9.AF.10 | Kanonaite | Mn3+Al(SiO4)O |
| 9.AF.10 | Andalusite | Al2(SiO4)O |
| 9.AF.15 | Kyanite | Al2(SiO4)O |
| 9.AF.20 | Krieselite | Al2(GeO4)F2 |
| 9.AF.20 | Mullite | Al4+2xSi2-2xO10-x |
| 9.AF.23 | Boromullite | Al9BSi2O19 |
| 9.AF.25 | Yoderite | Mg(Al,Fe3+)3(SiO4)2O(OH) |
| 9.AF.30 | Zincostaurolite | Zn2Al9Si4O23(OH) |
| 9.AF.30 | Staurolite | Fe2+2Al9Si4O23(OH) |
| 9.AF.30 | Magnesiostaurolite | Mg(Mg,Li)3(Al,Mg)18Si8O44(OH)4 |
| 9.AF.35 | Topaz | Al2(SiO4)(F,OH)2 |
| 9.AF.40 | Norbergite | Mg3(SiO4)F2 |
| 9.AF.45 | Chondrodite | Mg5(SiO4)2F2 |
| 9.AF.45 | Kumtyubeite | Ca5(SiO4)2F2 |
| 9.AF.45 | Reinhardbraunsite | Ca5(SiO4)2(OH,F)2 |
| 9.AF.45 | Hydroxylchondrodite | Mg5(SiO4)2(OH)2 |
| 9.AF.45 | Alleghanyite | Mn2+5(SiO4)2(OH)2 |
| 9.AF.50 | 'Unnamed (Ca-analogue of Humite)' | Ca7(SiO4)4F2 |
| 9.AF.50 | Humite | Mg7(SiO4)3F2 |
| 9.AF.50 | Manganhumite | Mn2+7(SiO4)3(OH)2 |
| 9.AF.50 | 'Unnamed (OH-analogue of humite)' | Mg7(SiO4)3(OH)2 |
| 9.AF.50 | Fluorchegemite | Ca7(SiO4)3F2 |
| 9.AF.55 | Hydroxylclinohumite | Mg9(SiO4)4(OH)2 |
| 9.AF.55 | Clinohumite | Mg9(SiO4)4F2 |
| 9.AF.55 | Sonolite | Mn2+9(SiO4)4(OH)2 |
| 9.AF.60 | Leucophoenicite | Mn2+7(SiO4)3(OH)2 |
| 9.AF.65 | Ribbeite | Mn2+5(SiO4)2(OH)2 |
| 9.AF.70 | Jerrygibbsite | Mn2+9(SiO4)4(OH)2 |
| 9.AF.75 | Scorticoite | Mn6(Sb,◻)Σ2(SiO4)2O3(OH)3 |
| 9.AF.75 | Welinite | Mn2+6(W6+,Mg)2(SiO4)2(O,OH)6 |
| 9.AF.75 | Örebroite | Mn2+3(Sb5+,Fe3+)(SiO4)(O,OH)3 |
| 9.AF.80 | Ellenbergerite | Mg6(Mg,Ti,Zr,◻)2(Al,Mg)6Si8O28(OH)10 |
| 9.AF.85 | Magnesiochloritoid | MgAl2O(SiO4)(OH)2 |
| 9.AF.85 | Ottrélite | Mn2+Al2O(SiO4)(OH)2 |
| 9.AF.85 | Chloritoid | Fe2+Al2O(SiO4)(OH)2 |
| 9.AF.90 | Olmiite | CaMn2+[SiO3(OH)](OH) |
| 9.AF.90 | Poldervaartite | CaCa[SiO3(OH)](OH) |
| 9.AF.95 | Pilawite-(Y) | Ca2Y2Al4(SiO4)4O2(OH)2 |
Other Information
Notes:
May be weakly magnetic, possibly resulting from tiny opaque inclusions.
Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.
Internet Links for Franciscanite
mindat.org URL:
https://www.mindat.org/min-1590.html
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References for Franciscanite
Reference List:
Dunn, Pete J., Peacor, Donald R., Erd, Richard C., Ramik, Robert A. (1986) Franciscanite and örebroite, two new minerals from California and Sweden, related to redefined welinite. American Mineralogist, 71 (11-12). 1522-1526
Localities for Franciscanite
Showing 5 localities.
symbol to view information about a locality.
The Locality List
- This locality has map coordinates listed.
- This locality has estimated coordinates.
ⓘ - Click for references and further information on this occurrence.
? - Indicates mineral may be doubtful at this locality.
- Good crystals or important locality for species.
- World class for species or very significant.
(TL) - Type Locality for a valid mineral species.
(FRL) - First Recorded Locality for everything else (eg varieties).
All localities listed without proper references should be considered as questionable.
Italy | |
| Balestra et al. (2009) |
Japan | |
| Yamada et al (2000) |
Spain | |
| Dill et al. (2023) |
| Dill et al. (2023) | |
USA (TL) | |
| Dunn et al. (1986) +1 other reference |
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Pennsylvania Mine, Sugarloaf Mountain, Black Wonder Mining District, Santa Clara County, California, USA