Frondelite
A valid IMA mineral species - grandfathered
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About Frondelite
Clifford Frondel
Formula:
(Mn2+0.5Fe3+0.5)2Fe3+3(PO4)3(OH)5
Previously given as Mn2+Fe3+4(PO4)3(OH)5.
Colour:
Dark brown, ocher-yellow, red-brown, greenish black, greenish brown, black; rarely orange
Lustre:
Vitreous, Sub-Vitreous, Resinous, Greasy, Dull
Hardness:
4½
Specific Gravity:
3.453
Crystal System:
Orthorhombic
Member of:
Name:
Named in 1949 by Marie Louise Lindberg (later Smith) in honor of Clifford Frondel (January 8, 1907 Brooklyn, New York, New York, USA - November 12, 2002 Winchester, Massachusetts, USA), American mineralogist, Professor of Mineralogy, Harvard University, Cambridge, Massachusetts, USA.
The mineral cliffordite is also named in his honor.
The mineral cliffordite is also named in his honor.
Isostructural with:
Rockbridgeite Group. Frondelite-Rockbridgeite Series.
The Mn2+-analogue of rockbridgeite and plimerite.
A secondary mineral resulting from the alteration of primary phosphates in complex granitic pegmatites.
The Mn2+-analogue of rockbridgeite and plimerite.
A secondary mineral resulting from the alteration of primary phosphates in complex granitic pegmatites.
Unique Identifiers
Mindat ID:
1614
Long-form identifier:
mindat:1:1:1614:4
IMA Classification of Frondelite
Approved, 'Grandfathered' (first described prior to 1959)
First published:
1949
Classification of Frondelite
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
41.9.2.2
41 : ANHYDROUS PHOSPHATES, ETC.CONTAINING HYDROXYL OR HALOGEN
9 : (AB)5(XO4)3Zq
41 : ANHYDROUS PHOSPHATES, ETC.CONTAINING HYDROXYL OR HALOGEN
9 : (AB)5(XO4)3Zq
19.12.15
19 : Phosphates
12 : Phosphates of Mn
19 : Phosphates
12 : Phosphates of Mn
Mineral Symbols
As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.
Please only use the official IMA–CNMNC symbol. Older variants are listed for historical use only.
Please only use the official IMA–CNMNC symbol. Older variants are listed for historical use only.
| Symbol | Source | Reference for Standard |
|---|---|---|
| Fnd | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
| Fnd | The Canadian Mineralogist (2019) | The Canadian Mineralogist (2019) The Canadian Mineralogist list of symbols for rock- and ore-forming minerals (December 30, 2019). download |
Physical Properties of Frondelite
Vitreous, Sub-Vitreous, Resinous, Greasy, Dull
Transparency:
Translucent
Colour:
Dark brown, ocher-yellow, red-brown, greenish black, greenish brown, black; rarely orange
Comment:
Colour zoning lengthwise common, manifests as concentric banding in radial aggregates.
Streak:
Green (unoxidized), brown (oxidized)
Hardness:
4½ on Mohs scale
Tenacity:
Brittle
Cleavage:
Very Good
On {100}, excellent; on {010}, good; on {001}, fair.
On {100}, excellent; on {010}, good; on {001}, fair.
Fracture:
Irregular/Uneven, Splintery, Fibrous
Density:
3.453 g/cm3 (Measured) 3.35 g/cm3 (Calculated)
Optical Data of Frondelite
Type:
Biaxial (-)
RI values:
nα = 1.860 nβ = 1.880 nγ = 1.893
2V:
Measured: 45°
Birefringence:
0.033
Max. Birefringence:
δ = 0.033
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:
r > v strong
Optical Extinction:
Parallel
Pleochroism:
Visible
Comments:
X = Light yellow-brown
Y = Orange-brown
Z = Orange-brown
Y = Orange-brown
Z = Orange-brown
Comments:
Much so-called frondelite is Fe2+>Mn2+ and therefore is rockbridgeite.
Chemistry of Frondelite
Mindat Formula:
(Mn2+0.5Fe3+0.5)2Fe3+3(PO4)3(OH)5
Previously given as Mn2+Fe3+4(PO4)3(OH)5.
Previously given as Mn2+Fe3+4(PO4)3(OH)5.
Element Weights:
Crystallography of Frondelite
Crystal System:
Orthorhombic
Class (H-M):
222 - Disphenoidal
Space Group:
C2221
Cell Parameters:
a = 13.810 Å, b = 16.968 Å, c = 5.182 Å
Ratio:
a:b:c = 0.814 : 1 : 0.305
Unit Cell V:
1,214.29 ų (Calculated from Unit Cell)
Z:
4
Morphology:
Euhedral crystals rare. Crystals exhibit {100}, {010}, {110}, and {101}. Typically fibrous, elongated along [001]; radiating, in crusts, botyroidal and drusy masses.
Comment:
B2212
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 6.91 Å | (17) |
| 3.615 Å | (40) |
| 3.445 Å | (25) |
| 3.381 Å | (85) |
| 3.191 Å | (100) |
| 3.046 Å | (20) |
| 1.5953 Å | (19) |
Comments:
ICDD 35-625
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] |
Geological Setting:
Granitic pegmatites.
Type Occurrence of Frondelite
General Appearance of Type Material:
Crusts and as botryoidal and drusy masses, showing in cross section a radiating fibrous structure.
Place of Conservation of Type Material:
Harvard University, Cambridge, Massachusetts, USA - #100808.
National Museum of Natural History (Smithsonian), Washington, D.C., USA - #105946.
National Museum of Natural History (Smithsonian), Washington, D.C., USA - #105946.
Geological Setting of Type Material:
Granitic pegmatite.
Associated Minerals at Type Locality:
Other Language Names for Frondelite
Relationship of Frondelite to other Species
Member of:
Other Members of Rockbridgeite Group:
| Ferrirockbridgeite | (Fe3+0.67◻0.33)2(Fe3+)3(PO4)3(OH)4(H2O) | Orth. mmm(2/m2/m2/m) |
| Ferrorockbridgeite | (Fe2+,Mn2+)2(Fe3+)3(PO4)3(OH)4(H2O) | Orth. mmm(2/m2/m2/m) |
| 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) |
Forms a series with:
Common Associates
Associations Based on Photo Data:
| 34 photos of Frondelite associated with Phosphosiderite | FePO4 · 2H2O |
| 13 photos of Frondelite associated with Strengite | FePO4 · 2H2O |
| 13 photos of Frondelite associated with Mitridatite | Ca2Fe3+3(PO4)3O2 · 3H2O |
| 12 photos of Frondelite associated with Lindbergite | Mn2+(C2O4) · 2H2O |
| 11 photos of Frondelite associated with Variscite | AlPO4 · 2H2O |
| 10 photos of Frondelite associated with Cyrilovite | NaFe3+3(PO4)2(OH)4 · 2H2O |
| 8 photos of Frondelite associated with Quartz | SiO2 |
| 7 photos of Frondelite associated with Bermanite | Mn2+Mn3+2(PO4)2(OH)2 · 4H2O |
| 5 photos of Frondelite associated with Hureaulite | Mn2+5(PO3OH)2(PO4)2 · 4H2O |
| 5 photos of Frondelite associated with Leucophosphite | KFe3+2(PO4)2(OH) · 2H2O |
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 | Rockbridgeite | (Fe2+0.5Fe3+0.5)2Fe3+3(PO4)3(OH)5 |
| 8.BC.10 | Ferrirockbridgeite | (Fe3+0.67◻0.33)2(Fe3+)3(PO4)3(OH)4(H2O) |
| 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 |
Fluorescence of Frondelite
Not Fluorescent in UV
Other Information
Notes:
Soluble in HCl but not in HNO3 or H2SO4.
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 Frondelite
mindat.org URL:
https://www.mindat.org/min-1614.html
Please feel free to link to this page.
Please feel free to link to this page.
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References for Frondelite
Reference List:
Lindberg, Marie Louise (1949) Frondelite and the frondelite-rockbridgeite series. American Mineralogist, 34 (7-8) 541-549
Frost, Ray L., Xi, Yunfei, Scholz, Ricardo, Belotti, Fernanda M., Beganovic, Martina (2013) SEM–EDX, Raman and infrared spectroscopic characterization of the phosphate mineral frondelite (Mn2+)(Fe3+)4(PO4)3(OH)5. Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 110. 7-13 doi:10.1016/j.saa.2013.02.008
Localities for Frondelite
Showing 68 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.
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Sítio do Castelo Mine, Folgosinho, Gouveia, Guarda, Portugal