Black (from organic inclusions; pale to dark brown in thin section
Crystal habit
Rarely as crystals, commonly as colloform to botryoidal incrustations, fibrous, pulverulent masses
Fracture
Irregular to subconchoidal
Tenacity
Brittle to friable
Mohs scale hardness
5–6
Luster
Dull to adamantine
Streak
Grayish black
Diaphaneity
Opaque, transparent on thin edges
Specific gravity
5.1
Optical properties
Uniaxial (+/−)
Refractive index
nα = 1.730–1.750 nβ = 1.730–1.750
Birefringence
δ = 1.730
Pleochroism
Moderate; pale yellow-brown parallel to and medium brown perpendicular to long axis
Alters to
Metamict
Other characteristics
Radioactive
72.63% (U)
References
[2][3][4][5][6][7][8][9][10][11][12][13][14]
Coffinite is a uranium-bearing silicate mineral with formula: U(SiO4)1−x(OH)4x.
It occurs as black incrustations, dark to pale-brown in thin section. It has a grayish-black streak. It has a brittle to conchoidal fracture. The hardness of coffinite is between 5 and 6.
It was first described in 1954 for an occurrence at the La Sal No. 2 Mine, Beaver Mesa, Mesa County, Colorado, US,[5] and named for American geologist Reuben Clare Coffin (1886–1972).[3]
It has widespread global occurrence in Colorado Plateau-type uranium ore deposits of uranium and vanadium. It replaces organic matter in sandstone and in hydrothermal vein type deposits.[3] It occurs in association with uraninite, thorite, pyrite, marcasite, roscoelite, clay minerals and amorphous organic matter.[3]
^ abcdAnthony, John W.; Bideaux, Richard A.; Bladh, Kenneth W.; Nichols, Monte C. (2005). "Coffinite" (PDF). Handbook of Mineralogy. Mineral Data Publishing. Retrieved 19 June 2022.
^Webmineral data
^ abCoffinite, Mindat.org
^Stieff, L.R.; Stern, T.W; Sherwood, A.M. (1955). "Preliminary Description of Coffinite – A New Uranium Mineral". Science. 121 (3147): 608–609. Bibcode:1955Sci...121..608S. doi:10.1126/science.121.3147.608-a. hdl:2027/mdp.39015095016906.
^Fuchs, L.H.; Gebert, E. (1958). "X-Ray Studies of Synthetic Coffinite, Thorite and Uranothorites". American Mineralogist. 43: 243–248.
^Stieff, L.R.; Stern, T.W; Sherwood, A.M. (1956). "Coffinite, a Uranous Silicate with Hydroxyl Substitution – A New Mineral". American Mineralogist. 41: 675–688.
^Hansley, P.L.; Fitzpatrick, J.J. (1989). "Compositional and Crystallographic Data on REE-Bearing Coffinite from the Grants Uranium Region, Northwestern New-Mexico". American Mineralogist. 74: 263–270.
^Moench, R.H. (1962). "Properties and Paragenesis af Coffinite from Woodrow Mine, New Mexico". American Mineralogist. 47: 26–33.
^Min, M.Z.; Fang, C.Q.; Fayek, M. (2005). "Petrography and Genetic History of Coffinite and Uraninite from the Liueryiqi Granite-Hosted Uranium Deposit, SE China". Ore Geology Reviews. 26 (3–4): 187–197. doi:10.1016/j.oregeorev.2004.10.006.
^Zhang, F. X.; Pointeau, V.; Shuller, L. C.; et al. (2009). "Response of Synthetic Coffinite to Energetic Ion Beam Irradiation". American Mineralogist. 94: 916–920. doi:10.2138/am.2009.3111. S2CID 73581946.
Coffinite is a uranium-bearing silicate mineral with formula: U(SiO4)1−x(OH)4x. It occurs as black incrustations, dark to pale-brown in thin section....
and torbernite (with copper); and hydrated uranium silicates such as coffinite, uranophane (with calcium) and sklodowskite (magnesium). There are several...
common uranium ore), carnotite, autunite, uranophane, torbernite, and coffinite. Significant concentrations of uranium occur in some substances such as...
caldera's southwestern edge. The uranium ore minerals include uraninite and coffinite. The age of the uranium formation is assumed to be the same as the caldera...
trachyrhyolite. Uranium ore bodies are found in the Dornod, consisting of coffinite and pitchblende. "Uranium in Mongolia". World Nuclear Association. January...
the secondary minerals autunite and meta-autunite after uraninite and coffinite in fractured Cambrian metamorphosed shales and quartzite, at or near the...
Paleocene Fort Union Formation. The principal ore minerals are uraninite, coffinite, metatyuyamunite, and carnotite. Gangue minerals are calcite, gypsum,...
silica rich aqueous solution forms uranium dioxide, uranium trioxide, and coffinite. In pure water, schoepite (UO2)8O2(OH)12·12(H2O) is formed in the first...
is a palaeochannel uranium deposit. The uranium mineralisation (mainly coffinite) is hosted by loose sands in the channel of a former river. The ore bearing...
uraninite (most common uranium ore), autunite, uranophane, torbernite, and coffinite. Significant concentrations of uranium occur in some substances such as...
the Triassic Chinle Formation. Primary ore minerals are uraninite and coffinite. Through 1965, the White Canyon district produced 10 million pounds (4...
contact. Shallow ore is mainly autunite. Deeper ore is pitchblende and coffinite with abundant pyrite and marcasite. Uranium minerals occur disseminated...
Wiang area of Khon Kaen province and discovered a type of uranium ore, coffinite, in association with copper ores, azurite and malachite. The International...
resources of titanium and niobium in the United States." 1954 uranium Gateway Coffinite was first identified by Thomas W. Stern of the US Geological Survey in...
weakly radioactive. The radioactivity is mostly caused by tiny specks of coffinite in the paramontroseite. When a section is polished the paramontroseite...
Taylor Mine for development by in-situ leaching. Uranium is present in coffinite in the Westwater Canyon member of the Morrison Formation at 3,000 feet...
survey. Uranium was present as meta-autunite, uranophane, uraninite, and coffinite in tufaceous fluvial sandstones of the Miocene Browns Park Formation....
mineral forms in the weathering zone as an oxidation product of uraninite-coffinite, in the presence of an oxidizing pyrite, where the pH is greater than...
development by in-situ leaching; there are potentially large deposits of coffinite and uranium oxide ores available in New Mexico. New Mexico has enacted...
Global Information
Radioactive
72.63% (U)