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Ferrirockbridgeite
A valid IMA mineral species
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About Ferrirockbridgeite
Formula:
(Fe3+0.67◻0.33)2(Fe3+)3(PO4)3(OH)4(H2O)
Colour:
Reddish-brown
Specific Gravity:
3.33
Crystal System:
Orthorhombic
Member of:
Name:
For the root name of rockbridgeite and the ferric iron content.
Fe3+-vacancy-analogue of ferrorockbridgeite. One of few known fully ferric-iron hydrous hydrated phosphate minerals, chemically comparable to allanpringite, beraunite, ferristrunzite, santabarbaraite, and tinticite.
Unique Identifiers
Mindat ID:
53168
Long-form identifier:
mindat:1:1:53168:5
Similar Names
| Ferrorockbridgeite | A valid IMA mineral species | (Fe2+,Mn2+)2(Fe3+)3(PO4)3(OH)4(H2O) |
IMA Classification of Ferrirockbridgeite
Approved
IMA Formula:
(Fe3+0.67◻0.33)2(Fe3+)3(PO4)3(OH)4(H2O)
Approval year:
2018
First published:
2019
Type description reference:
Grey, Ian Edward, Kampf, Anthony R., Keck, Erich, Cashion, John D., MacRae, Colin M., Gozukara, Yesim, Shanks, Finlay L. (2019) Ferrirockbridgeite, (Fe3+0.67□0.33)2(Fe3+)3(PO4)3(OH)4(H2O), and the oxidation mechanism for rockbridgeite-group minerals. European Journal of Mineralogy, 31 (3) 585-594 doi:10.1127/ejm/2019/0031-2846
Classification of Ferrirockbridgeite
8.BC.10
8 : PHOSPHATES, ARSENATES, VANADATES
B : Phosphates, etc., with additional anions, without H2O
C : With only medium-sized cations, (OH, etc.):RO4 > 1:1 and < 2:1
8 : PHOSPHATES, ARSENATES, VANADATES
B : Phosphates, etc., with additional anions, without H2O
C : With only medium-sized cations, (OH, etc.):RO4 > 1:1 and < 2:1
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 |
|---|---|---|
| Frck | 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 Ferrirockbridgeite
Colour:
Reddish-brown
Density:
3.33 g/cm3 (Measured) 3.42 g/cm3 (Calculated)
Comment:
Measured using Berman balance with toluene. The low measured value is due to sub-micron porosity.
Optical Data of Ferrirockbridgeite
Type:
Biaxial (-)
RI values:
nα = 1.875(5) nβ = 1.890 nγ = 1.900(5)
2V:
Measured: 78° (1)
Max. Birefringence:
δ = 0.025
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:
Very High (positive)
Relative to Canada balsam mounting medium (n ≈ 1.537).
Relative to Canada balsam mounting medium (n ≈ 1.537).
This shows the grain boundary and Becke line effect under plane-polarised
light, based on the contrast between this mineral's average refractive
index and the mounting medium. It does not take into account mineral
colouration.
In focus
Interference Figure:
This shows the idealized biaxial acute bisectrix (Bxa) interference figure
- the conoscopic view for a grain cut perpendicular to the acute bisectrix, using
this mineral's 2V. The two small white dots mark the melatopes - the points
where the two optic axes emerge - and are shown only when they fall within the
field of view. The coloured bands are isochromatics, and the dark bands are
isogyres.
Rotate the stage: at 0°/90° the isogyres form a cross through the melatopes; at 45° they pull apart into curved hyperbolas. That splitting on rotation - absent in a uniaxial figure - is the standard diagnostic test for telling biaxial minerals from uniaxial ones. If 2V is large, the melatopes may fall outside the field of view, as they often do at the microscope too.
Rotate the stage: at 0°/90° the isogyres form a cross through the melatopes; at 45° they pull apart into curved hyperbolas. That splitting on rotation - absent in a uniaxial figure - is the standard diagnostic test for telling biaxial minerals from uniaxial ones. If 2V is large, the melatopes may fall outside the field of view, as they often do at the microscope too.
Dispersion:
Strong, with r > v
Pleochroism:
Visible
Comments:
X = yellow brown, Y = olive brown, Z = dark olive green
Comments:
β calculated.
Orientation: X = c, Y = a, Z = b.
Absorption: Z > Y > X.
Orientation: X = c, Y = a, Z = b.
Absorption: Z > Y > X.
Chemistry of Ferrirockbridgeite
Mindat Formula:
(Fe3+0.67◻0.33)2(Fe3+)3(PO4)3(OH)4(H2O)
Element Weights:
Elements listed:
Crystallography of Ferrirockbridgeite
Crystal System:
Orthorhombic
Class (H-M):
mmm(2/m2/m2/m) - Dipyramidal
Cell Parameters:
a = 13.853(1) Å, b = 16.928(1) Å, c = 5.1917(5) Å
Ratio:
a:b:c = 0.818 : 1 : 0.307
Unit Cell V:
1,217.47 ų (Calculated from Unit Cell)
Z:
4
Morphology:
Blade-like crystals, flattened on {010} and elongated on [001].
Comment:
space group is Bbmm
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 6.994 Å | (21) |
| 4.853 Å | (26) |
| 3.615 Å | (24) |
| 3.465 Å | (33) |
| 3.424 Å | (39) |
| 3.205 Å | (100) |
| 2.774 Å | (22) |
| 1.603 Å | (24) |
Reference:
Grey, Ian Edward, Kampf, Anthony R., Keck, Erich, Cashion, John D., MacRae, Colin M., Gozukara, Yesim, Shanks, Finlay L. (2019) Ferrirockbridgeite, (Fe3+0.67□0.33)2(Fe3+)3(PO4)3(OH)4(H2O), and the oxidation mechanism for rockbridgeite-group minerals. European Journal of Mineralogy, 31 (3) 585-594 doi:10.1127/ejm/2019/0031-2846
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Near-surface Processes | |
| 22 : Hydration and low-? subsurface aqueous alteration (see also #23) | |
| Stage 4b: Highly evolved igneous rocks | >3.0 |
| 34 : Complex granite pegmatites | |
| Stage 7: Great Oxidation Event | <2.4 |
| 47a : [Near-surface hydration of prior minerals] | |
| 47c : [Carbonates, phosphates, borates, nitrates] |
Type Occurrence of Ferrirockbridgeite
General Appearance of Type Material:
Radial fibrous crusts and masses. Compact intergrowths of reddish-brown blade-like crystals.
Place of Conservation of Type Material:
Collections of the Mineralogical and Geological Museum, Harvard University, 20 Oxford Street, Cambridge, MA 02138, USA, catalogue number 95086.
Geological Setting of Type Material:
Oxidized zone of a granitic pegmatite. Highly oxidized alteration of triphylite.
Associated Minerals at Type Locality:
Reference:
Grey, Ian Edward, Kampf, Anthony R., Keck, Erich, Cashion, John D., MacRae, Colin M., Gozukara, Yesim, Shanks, Finlay L. (2019) Ferrirockbridgeite, (Fe3+0.67□0.33)2(Fe3+)3(PO4)3(OH)4(H2O), and the oxidation mechanism for rockbridgeite-group minerals. European Journal of Mineralogy, 31 (3) 585-594 doi:10.1127/ejm/2019/0031-2846
Synonyms of Ferrirockbridgeite
Other Language Names for Ferrirockbridgeite
Dutch:Ferrirockbridgeiet
German:Ferrirockbridgeit
Relationship of Ferrirockbridgeite to other Species
Member of:
Other Members of Rockbridgeite Group:
| Ferrorockbridgeite | (Fe2+,Mn2+)2(Fe3+)3(PO4)3(OH)4(H2O) | Orth. mmm(2/m2/m2/m) |
| Frondelite | (Mn2+0.5Fe3+0.5)2Fe3+3(PO4)3(OH)5 | Orth. 222 : C2221 |
| Manganrockbridgeite | Mn2+2Fe3+3(PO4)3(OH)4(H2O) | Mon. 2/m : P21/m |
| Plimerite | ZnFe3+4(PO4)3(OH)5 | Orth. mmm(2/m2/m2/m) |
| Rockbridgeite | (Fe2+0.5Fe3+0.5)2Fe3+3(PO4)3(OH)5 | Orth. mmm(2/m2/m2/m) |
Common Associates
Associations Based on Photo Data:
| 3 photos of Ferrirockbridgeite associated with Rockbridgeite | (Fe2+0.5Fe3+0.5)2Fe3+3(PO4)3(OH)5 |
| 3 photos of Ferrirockbridgeite associated with Siderite | FeCO3 |
Related Minerals - Strunz-mindat Grouping
| 8.BC. | Manganrockbridgeite | Mn2+2Fe3+3(PO4)3(OH)4(H2O) |
| 8.BC. | Elaliite | (Fe2+8Fe3+)(PO4)O8 |
| 8.BC. | Elkinstantonite | Fe4(PO4)2O |
| 8.BC.05 | Leybovite-K | KCuNa(MgFe3+)(AsO4)3 |
| 8.BC.05 | Angelellite | Fe3+4(AsO4)2O3 |
| 8.BC.10 | Frondelite | (Mn2+0.5Fe3+0.5)2Fe3+3(PO4)3(OH)5 |
| 8.BC.10 | Rockbridgeite | (Fe2+0.5Fe3+0.5)2Fe3+3(PO4)3(OH)5 |
| 8.BC.10 | Ferrorockbridgeite | (Fe2+,Mn2+)2(Fe3+)3(PO4)3(OH)4(H2O) |
| 8.BC.10 | Plimerite | ZnFe3+4(PO4)3(OH)5 |
| 8.BC.15 | Aerugite | Ni8.5(AsO4)2As5+O8 |
Other Information
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 Ferrirockbridgeite
mindat.org URL:
https://www.mindat.org/min-53168.html
Please feel free to link to this page.
Please feel free to link to this page.
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References for Ferrirockbridgeite
Reference List:
Hålenius, U., Hatert, F., Pasero, M., Mills, S. J. (2018) CNMNC Newsletter 45, New minerals and nomenclature modifications approved in 2018. Mineralogical Magazine, 82 (5) 1225-1232 doi:10.1180/mgm.2018.160p.1230
Grey, Ian Edward, Kampf, Anthony R., Keck, Erich, Cashion, John D., MacRae, Colin M., Gozukara, Yesim, Shanks, Finlay L. (2019) Ferrirockbridgeite, (Fe3+0.67□0.33)2(Fe3+)3(PO4)3(OH)4(H2O), and the oxidation mechanism for rockbridgeite-group minerals. European Journal of Mineralogy, 31 (3) 585-594 doi:10.1127/ejm/2019/0031-2846
Localities for Ferrirockbridgeite
Showing 2 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.
Germany | |
| Grey et al. (2019) |
USA (TL) | |
| Grey et al. (2019) |
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Palermo No. 1 Mine, Groton, Grafton County, New Hampshire, USA