Coffinite
A valid IMA mineral species - grandfathered
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About Coffinite
Reuben Clare Coffin
Formula:
U(SiO4) · nH2O
Also given as (U4+,Th)(SiO4)1-x(OH)4x
Colour:
Black
Lustre:
Adamantine
Hardness:
5 - 6
Specific Gravity:
5.1
Crystal System:
Tetragonal
Member of:
Name:
Named in honor of Reuben Clare Coffin (29 October 1886, Longmont, Colorado, USA - 10 September 1972, Tulsa, Oklahoma, USA), geologist, for his outstanding geologic studies in southwestern Colorado. He worked as Chief Geologist of the Midwest Refining Company, later the Stanolind Oil and Gas company, and consultant to USGS.
Unique Identifiers
Mindat ID:
1106
Long-form identifier:
mindat:1:1:1106:4
Similar Names
| Koivinite | A synonym of 'Florencite' |
| Koivinite-(Y) | A discredited species name |
IMA Classification of Coffinite
Approved, 'Grandfathered' (first described prior to 1959)
IMA Formula:
U4+(SiO4)·nH2O
First published:
1955
Classification of Coffinite
9.AD.30
9 : SILICATES (Germanates)
A : Nesosilicates
D : Nesosilicates without additional anions; cations in [6] and/or greater coordination
9 : SILICATES (Germanates)
A : Nesosilicates
D : Nesosilicates without additional anions; cations in [6] and/or greater coordination
51.5.2.4
51 : NESOSILICATES Insular SiO4 Groups Only
5 : Insular SiO4 Groups Only with cations in >[6] coordination
51 : NESOSILICATES Insular SiO4 Groups Only
5 : Insular SiO4 Groups Only with cations in >[6] coordination
14.16.2
14 : Silicates not Containing Aluminum
16 : Silicates of U
14 : Silicates not Containing Aluminum
16 : Silicates of U
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 |
|---|---|---|
| Cof | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
| Cof | 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 Coffinite
Adamantine
Transparency:
Opaque
Colour:
Black
Comment:
Transmitted light the smaller particles of coffinite-bearing material are pale brown to very dark brown on thin edges.
Hardness:
5 - 6 on Mohs scale
Tenacity:
Brittle
Fracture:
Irregular/Uneven, Sub-Conchoidal
Density:
5.1 g/cm3 (Measured)
Optical Data of Coffinite
Type:
Uniaxial (+/-)
RI values:
nα = 1.73 - 1.75 nβ = 1.73 - 1.75
Surface Relief:
Unknown
Pleochroism:
Visible
Comments:
Moderate; pale yellow-brown parallel to length, medium brown perdendicular to length.
Chemistry of Coffinite
Mindat Formula:
U(SiO4) · nH2O
Also given as (U4+,Th)(SiO4)1-x(OH)4x
Also given as (U4+,Th)(SiO4)1-x(OH)4x
Element Weights:
Elements listed:
Common Impurities:
Al,Fe,As,V,Pb
Crystallography of Coffinite
Crystal System:
Tetragonal
Class (H-M):
4/mmm(4/m2/m2/m) - Ditetragonal Dipyramidal
Space Group:
I41/amd
Setting:
I41/amd
Cell Parameters:
a = 6.979 Å, c = 6.252 Å
Ratio:
a:c = 1 : 0.896
Unit Cell V:
304.51 ų (Calculated from Unit Cell)
Z:
4
Morphology:
Extremely fine grained to massive. In colloform or botryoidal incrustations, radially fibrous.
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) |
|---|---|---|---|---|---|---|---|
| 0000083 | Coffinite | Fuchs L H, Gebert E (1958) X-ray studies of synthetic coffinite, thorite and uranothorites American Mineralogist 43 243-248 |  | 1958 | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 3.48 Å | (100) |
| 4.64 Å | (95) |
| 2.636 Å | (95) |
| 1.803 Å | (70) |
| 2.789 Å | (45) |
| 1.849 Å | (35) |
| 1.738 Å | (35) |
Comments:
Synthetic. Natural material gives broad peaks or may be metamict.
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Near-surface Processes | |
| 23 : Subaerial aqueous alteration by non-redox-sensitive fluids (see also #47) | |
| Stage 10a: Neoproterozoic oxygenation/terrestrial biosphere | <0.6 |
| 53 : Other minerals with taphonomic origins | <0.4 |
Geological Setting:
unoxidized uranium deposits
Type Occurrence of Coffinite
General Appearance of Type Material:
Fine grained. Often visually indistinguishable from uraninite.
Place of Conservation of Type Material:
The Natural History Museum, London, England, 1956,201; National Museum of Natural History, Washington, D.C., USA, 112646.
Geological Setting of Type Material:
Unoxidized uranium deposit. Replacements of organic material and as disseminations in sandstone.
Associated Minerals at Type Locality:
Other Language Names for Coffinite
Varieties of Coffinite
| Zirconium- and Yttrium-bearing Coffinite | The ZrO2 and Y2O3 contents reach 13.8 and 3.4 wt.%, respectively (René, 2015). |
Relationship of Coffinite to other Species
Member of:
Other Members of Zircon Group:
| Hafnon | Hf(SiO4) | Tet. 4/mmm(4/m2/m2/m) : I41/amd |
| Reidite | Zr(SiO4) | Tet. 4/m : I41/a |
| Stetindite-(Ce) | Ce4+SiO4 | Tet. 4/mmm(4/m2/m2/m) : I41/amd |
| Thorite | Th(SiO4) | Tet. 4/mmm(4/m2/m2/m) : I41/amd |
| Zircon | Zr(SiO4) | Tet. 4/mmm(4/m2/m2/m) : I41/amd |
Forms a series with:
Common Associates
Associations Based on Photo Data:
| 19 photos of Coffinite associated with Uraninite | UO2 |
| 6 photos of Coffinite associated with Boltwoodite | (K,Na)(UO2)(SiO3OH) · 1.5H2O |
| 5 photos of Coffinite associated with Thorite | Th(SiO4) |
| 5 photos of Coffinite associated with Uranophane | Ca(UO2)2(SiO3OH)2 · 5H2O |
| 4 photos of Coffinite associated with Allanite-(Y) | (CaY)(AlAlFe2+)O[Si2O7][SiO4](OH) |
| 4 photos of Coffinite associated with Eucairite | AgCuSe |
| 4 photos of Coffinite associated with Clausthalite | PbSe |
| 3 photos of Coffinite associated with Pyrite | FeS2 |
| 3 photos of Coffinite associated with Berzelianite | Cu2-xSe (x ≈ 0.12) |
| 3 photos of Coffinite associated with Tyuyamunite | Ca(UO2)2(VO4)2 · 5-8H2O |
Related Minerals - Strunz-mindat Grouping
| 9.AD. | Adrianite | Ca12(Al4Mg3Si7)O32Cl6 |
| 9.AD.05 | Larnite | Ca2SiO4 |
| 9.AD.10 | Calcio-olivine | Ca2SiO4 |
| 9.AD.15 | Merwinite | Ca3Mg(SiO4)2 |
| 9.AD.20 | Bredigite | Ca7Mg(SiO4)4 |
| 9.AD.25 | Midbarite | Ca3Mg2(V5+2Si)O12 |
| 9.AD.25 | Menzerite-(Y) | (Y2Ca)Mg2(SiO4)3 |
| 9.AD.25 | Uvarovite | Ca3Cr3+2(SiO4)3 |
| 9.AD.25 | Eltyubyuite | Ca12Fe3+10Si4O32Cl6 |
| 9.AD.25 | Eringaite | Ca3Sc2(SiO4)3 |
| 9.AD.25 | Henritermierite | Ca3Mn3+2(SiO4)2[◻(OH)4] |
| 9.AD.25 va | 'Hydrougrandite' | (Ca,Mg,Fe2+)3(Fe3+,Al)2[(OH)4(SiO4)2] |
| 9.AD.25 | Calderite | Mn2+3Fe3+2(SiO4)3 |
| 9.AD.25 | Nikmelnikovite | Ca12(Fe2+Fe3+3Al3◻)[SiO4]6[◻(OH)4]5◻4 |
| 9.AD.25 | Hutcheonite | Ca3Ti2(SiO4)(AlO4)2 |
| 9.AD.25 | Wadalite | (Ca,Mg)6(Al,Fe3+)4((Si,Al)O4)3O4Cl3 |
| 9.AD.25 | Rubinite | Ca3Ti3+2(SiO4)3 |
| 9.AD.25 | Kerimasite | Ca3Zr2(SiO4)(Fe3+O4)2 |
| 9.AD.25 | Holtstamite | Ca3Al2(SiO4)2[◻(OH)4] |
| 9.AD.25 | Spessartine | Mn2+3Al2(SiO4)3 |
| 9.AD.25 | Toturite | Ca3Sn2(SiO4)(Fe3+O4)2 |
| 9.AD.25 | Kimzeyite | Ca3Zr2(SiO4)(AlO4)2 |
| 9.AD.25 | 'Khoharite' | Mg3Fe3+2(SiO4)3 |
| 9.AD.25 | Irinarassite | Ca3Sn2(SiO4)(AlO4)2 |
| 9.AD.25 | Knorringite | Mg3Cr3+2(SiO4)3 |
| 9.AD.25 | Goldmanite | Ca3V3+2(SiO4)3 |
| 9.AD.25 | 'Blythite' | Mn2+3Mn3+2[SiO4]3 |
| 9.AD.25 | 'Skiagite' | Fe2+3Fe3+2[SiO4]3 |
| 9.AD.25 | 'UM1984-37-SiO:CrMn' | Mn2+3Cr3+2(SiO4)3 |
| 9.AD.25 | Almandine | Fe2+3Al2(SiO4)3 |
| 9.AD.25 va | 'Yamatoite' | (Mn2+,Ca)3(V3+,Al)2(SiO4)3 |
| 9.AD.25 | Momoiite | Mn2+3V3+2(SiO4)3 |
| 9.AD.25 | Grossular | Ca3Al2(SiO4)3 |
| 9.AD.25 | Andradite | Ca3Fe3+2(SiO4)3 |
| 9.AD.25 | Morimotoite | Ca3(TiFe2+)(SiO4)3 |
| 9.AD.25 | Majorite | Mg3(MgSi)(SiO4)3 |
| 9.AD.25 | Pyrope | Mg3Al2(SiO4)3 |
| 9.AD.25 | Schorlomite | Ca3Ti2(SiO4)(Fe3+O4)2 |
| 9.AD.30 | Hafnon | Hf(SiO4) |
| 9.AD.30 | Zircon | Zr(SiO4) |
| 9.AD.30 | Thorite | Th(SiO4) |
| 9.AD.30 va | 'Auerlite' | near Th(Si,P)O4 |
| 9.AD.30 | Stetindite-(Ce) | Ce4+SiO4 |
| 9.AD.35 | 'Tombarthite-(Y)' | Y4(Si,H4)4O12-x(OH)4+2x |
| 9.AD.35 | Huttonite | ThSiO4 |
| 9.AD.40 | Eulytine | Bi4(SiO4)3 |
| 9.AD.45 | Reidite | Zr(SiO4) |
| 9.AD.55 | Jeffbenite | Mg3Al2Si3O12 |
Radioactivity
Radioactivity:
| Element | % Content | Activity (Bq/kg) | Radiation Type |
|---|---|---|---|
| Uranium (U) | 68.3741% | 17,093,525 | α, β, γ |
| Thorium (Th) | 0.0000% | 0 | α, β, γ |
| Potassium (K) | 0.0000% | 0 | β, γ |
For comparison:
- Banana: ~15 Bq per fruit
- Granite: 1,000–3,000 Bq/kg
- EU exemption limit: 10,000 Bq/kg
Note: Risk is shown relative to daily recommended maximum exposure to non-background radiation of 1000 µSv/year. Note that natural background radiation averages around 2400 µSv/year so in reality these risks are probably extremely overstated! With infrequent handling and safe storage natural radioactive minerals do not usually pose much risk.
Interactive Simulator:
Note: The mass selector refers to the mass of radioactive mineral present, not the full specimen, also be aware that the matrix may also be radioactive, possibly more radioactive than this mineral!
Activity: –
| Distance | Dose rate | Risk |
|---|---|---|
| 1 cm | ||
| 10 cm | ||
| 1 m |
The external dose rate (D) from a radioactive mineral is estimated by summing the gamma radiation contributions from its Uranium, Thorium, and Potassium content, disregarding daughter-product which may have a significant effect in some cases (eg 'pitchblende'). This involves multiplying the activity (A, in Bq) of each element by its specific gamma ray constant (Γ), which accounts for its unique gamma emissions. The total unshielded dose at 1 cm is then scaled by the square of the distance (r, in cm) and multiplied by a shielding factor (μshield). This calculation provides a 'worst-case' or 'maximum risk' estimate because it assumes the sample is a point source and entirely neglects any self-shielding where radiation is absorbed within the mineral itself, meaning actual doses will typically be lower. The resulting dose rate (D) is expressed in microsieverts per hour (μSv/h).
D = ((AU × ΓU) + (ATh × ΓTh) + (AK × ΓK)) / r2 × μshield
Other Information
Notes:
Radioactive
Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.
Industrial Uses:
uranium ore
Internet Links for Coffinite
mindat.org URL:
https://www.mindat.org/min-1106.html
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References for Coffinite
Reference List:
STIEFF, L. R., STERN, T. W., SHERWOOD, A. M. (1955) Preliminary Description of Coffinite-- a New Uranium Mineral. Science, 121 (3147). 608-609 doi:10.1126/science.121.3147.608-a
STIEFF, L. R., STERN, T. W., SHERWOOD, A. M. (1955) Preliminary Description of Coffinite-- a New Uranium Mineral. Science, 121 (3147). 608-609 doi:10.1126/science.121.3147.608-a
Stieff, L. R., Stern, T. W., Sherwood, A. M. (1956) Coffinite, a uranous silicate with hydroxyl substitution: a new mineral. American Mineralogist, 41 (9-10) 675-688
HOEKSTRA, H. R., FUCHS, L. H. (1956) Synthesis of Coffinite--USiO4. Science, 123 (3186). 105 doi:10.1126/science.123.3186.105
Fuchs, L. H., Gebert, Elizabeth (1958) X-ray studies of synthetic coffinite, thorite and uranothorites. American Mineralogist, 43 (3-4) 243-248
Moench, Robert H. (1962) Properties and paragenesis of coffinite from the Woodrow mine, New Mexico. American Mineralogist, 47 (1-2) 26-33
Ramdohr, Paul (1969) The Ore Minerals and their Intergrowths. Pergamon Press, Oxford. 1174pp. doi:10.1016/c2013-0-10027-x
Janeczek, Janusz, Ewing, Rodney (1996) Phosphatian coffinite with rare earth elements and Ce-rich françoisite-(Nd) from sandstone beneath a natural fission reactor at Bangombé, Gabon. Mineralogical Magazine, 60 (401) 665-669 doi:10.1180/minmag.1996.060.401.14
Teterin, Yu. A.; Utkin, I. O.; Melnikov, I. V.; Lebedev, A. M.; Teterin, A. Yu.; Ivanov, K. E.; Nikitin, A. S.; Vukchevich, L. (2000) X-Ray Photoelectron Study of Thorium Silicate ThSiO4 · nH2O and Uranium Silicate USiO4·nH2O. Journal of Structural Chemistry, 41 (6). 965-971 doi:10.1023/a:1010302805492
Ondruš, P., Veselovský, F., Gabašová, A., Hloušek, J., Šrein, V., Vavřín, I., Skála, R., Sejkora, J., Drábek, M. (2003) Primary minerals of the Jáchymov ore district. Journal of the Czech Geological Society, 48 (3-4) 19-147
Förster, H.-J. (2006) Composition and origin of intermediate solid solutions in the system thorite–xenotime–zircon–coffinite. Lithos, 88 (1) 35-55 doi:10.1016/j.lithos.2005.08.003
Deditius, Artur P.; Utsunomiya, Satoshi; Ewing, Rodney C. (2008) The chemical stability of coffinite, USiO4·nH2O; 0<n<2, associated with organic matter: A case study from Grants uranium region, New Mexico, USA. Chemical Geology, 251 (1-4). 33-49 doi:10.1016/j.chemgeo.2008.02.009
Pointeau, V., Deditius, A.P., Miserque, F., Renock, D., Becker, U., Zhang, J., Clavier, N., Dacheux, N., Poinssot, C., Ewing, R.C. (2009) Synthesis and characterization of coffinite. Journal of Nuclear Materials, 393 (3). 449-458 doi:10.1016/j.jnucmat.2009.06.030
Deditius, Artur P.; Utsunomiya, Satoshi; Pointeau, Véronique; Ewing, Rodney C. (2010) Precipitation and alteration of coffinite (USiO4·nH2O) in the presence of apatite. European Journal of Mineralogy, 22 (1). 75-88 doi:10.1127/0935-1221/2010/0022-1990
Deditius, A. P., Pointeau, V., Zhang, J. M., Ewing, R. C. (2012) Formation of nanoscale Th-coffinite. American Mineralogist, 97 (4) 681-693 doi:10.2138/am.2012.3951
Clavier, N., Szenknect, S., Costin, D.T., Mesbah, A., Poinssot, C., Dacheux, N. (2014) From thorite to coffinite: A spectroscopic study of Th1−xUxSiO4 solid solutions. Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 118. 302-307 doi:10.1016/j.saa.2013.08.093
Baron, Fabien, Robin, Valentin, Beaufort, Daniel, Szenknect, Stéphanie, Dacheux, Nicolas, Petit, Sabine (2014) Use of near Infrared Spectroscopy for the Identification of Coffinite and Uranothorite. Journal of Near Infrared Spectroscopy, 22 (2) 149-152 doi:10.1255/jnirs.1110
Guo, Xiaofeng, Szenknect, Stéphanie, Mesbah, Adel, Labs, Sabrina, Clavier, Nicolas, Poinssot, Christophe, Ushakov, Sergey V., Curtius, Hildegard, Bosbach, Dirk, Ewing, Rodney C., Burns, Peter C., Dacheux, Nicolas, Navrotsky, Alexandra (2015) Thermodynamics of formation of coffinite, USiO4. Proceedings of the National Academy of Sciences, 112 (21) 6551-6555 doi:10.1073/pnas.1507441112
Mesbah, Adel; Szenknect, Stephanie; Clavier, Nicolas; Lozano-Rodriguez, Janeth; Poinssot, Christophe; Den Auwer, Christophe; Ewing, Rodney C.; Dacheux, Nicolas (2015) Coffinite, USiO4, Is Abundant in Nature: So Why Is It So Difficult To Synthesize? Inorganic Chemistry, 54 (14). p.6687-6696. doi:10.1021/ic502808n
Localities for Coffinite
Showing 816 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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Jackpile Mine, Laguna subdistrict, Cibola County, New Mexico, USA