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Coffinite

Formula:
(U,Th)[(OH)
 
4x
|(SiO
 
4
)
 
1-x
]
System:TetragonalHardness:5 - 6
This page provides mineralogical data about Coffinite.

Classification of Coffinite

IMA status:Valid - first described prior to 1959 (pre-IMA) - "Grandfathered"
Strunz 8th edition ID:8/A.09-40
Nickel-Strunz 10th (pending) edition ID:9.AD.30

9 : SILICATES (Germanates)
A : Nesosilicates
D : Nesosilicates without additional anions; cations in [6] and/or greater coordination
Dana 8th edition ID:51.5.2.4

51 : NESOSILICATES Insular SiO4 Groups Only
5 : Insular SiO4 Groups Only with cations in >[6] coordination
Hey's CIM Ref.:14.16.2

14 : Silicates not Containing Aluminum
16 : Silicates of U
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Type Occurrence of Coffinite

Type Locality:La Sal No. 2 Mine, Beaver Mesa, Mesa Co., Colorado, USA
Year of Discovery:1954

Physical Properties of Coffinite

Hardness (Mohs):5 - 6

Crystallography of Coffinite

Crystal System:Tetragonal
Cell Parameters:a = 6.97Å, c = 6.25Å
Ratio:a:c = 1 : 0.897
Unit Cell Volume:V 303.63 ų (Calculated from Unit Cell)

Optical Data of Coffinite

Type:Uniaxial (+/-)
RI values: nα = 1.730 - 1.750 nβ = 1.730 - 1.750
Maximum Birefringence:δ = 1.730

Chart shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
Surface Relief:High

Chemical Properties of Coffinite

Formula:
(U,Th)[(OH)
 
4x
|(SiO
 
4
)
 
1-x
]
Essential elements:H, O, Si, U
All elements listed in formula:H, O, Si, Th, U
Common Impurities:Al,Fe,As,V,Pb

Relationship of Coffinite to other Species

Related Minerals - Nickel-Strunz Grouping):
9.AD.05Larnite
Ca
 
2
[SiO
 
4
]
9.AD.05Calcio-Olivine
Ca
 
2
[SiO
 
4
]
9.AD.15Merwinite
Ca
 
3
Mg[SiO
 
4
]
 
2
9.AD.20Bredigite
Ca
 
7
Mg[SiO
 
4
]
 
4
9.AD.25Andradite
Ca
 
3
Fe
3+
2
[SiO
 
4
]
 
3
9.AD.25Almandine
Fe
2+
3
Al
 
2
[SiO
 
4
]
 
3
9.AD.25Calderite
(Mn
2+
 
,Ca)
 
3
(Fe
3+
 
,Al)
 
2
[SiO
 
4
]
 
3
9.AD.25Goldmanite
Ca
 
3
(V
3+
 
,Al,Fe
3+
 
)
 
2
[SiO
 
4
]
 
3
9.AD.25Grossular
Ca
 
3
Al
 
2
[SiO
 
4
]
 
3
9.AD.25Henritermierite
Ca
 
3
(Mn
3+
 
,Al)
 
2
[(OH)
 
4
|(SiO
 
4
)
 
2
]
9.AD.25Hibschite
Ca
 
3
Al
 
2
[(OH)
 
6-1
|(SiO
 
4
)
 
1.5-2.5
]
9.AD.25Hydroandradite
9.AD.25Katoite
Ca
 
3
Al
 
2
[(OH)
 
8-6
|(SiO
 
4
)
 
1-1.5
]
9.AD.25Kimzeyite
Ca
 
3
(Zr,Ti)
 
2
[(Si,Al,Fe
3+
 
)O
 
4
]
 
3
9.AD.25Knorringite
Mg
 
3
Cr
 
2
[SiO
 
4
]
 
3
9.AD.25Majorite
Mg
 
3
(Fe
2+
 
,Si,Al)
 
2
[SiO
 
4
]
 
3
9.AD.25Morimotoite
Ca
 
3
(Ti,Fe
2+
 
,Fe
3+
 
)
 
2
[(Si,Fe
3+
 
)O
 
4
]
 
3
(?)
9.AD.25Pyrope
Mg
 
3
Al
 
2
[SiO
 
4
]
 
3
9.AD.25Schorlomite
Ca
 
3
(Ti,Fe
3+
 
)
 
2
[(Si,Fe
3+
 
,Fe
2+
 
)O
 
4
]
 
3
9.AD.25Spessartine
Mn
2+
3
Al
 
2
[SiO
 
4
]
 
3
9.AD.25Uvarovite
Ca
 
3
Cr
 
2
[SiO
 
4
]
 
3
9.AD.25Wadalite
Ca
 
6
(Al,Mg)
 
4
[Cl
 
3
|O
 
4
|{(Si,Al,Fe
3+
 
)O
 
4
}
 
3
]
9.AD.25Holtstamite
Ca
 
3
(Al,Mn
3+
 
)
 
2
(SiO
 
4
)
 
2
(OH)
 
4
9.AD.30Hafnon
(Hf,Zr)[SiO
 
4
]
9.AD.30Thorite
(Th,U)[SiO
 
4
]
9.AD.30Thorogummite
(Th,U)[(OH)
 
4x
|(SiO
 
4
)
 
1-x
]
9.AD.30Zircon
Zr[SiO
 
4
]
9.AD.35Huttonite
Th[SiO
 
4
]
9.AD.35Tombarthite-(Y)
Y
 
4
[HSiO
 
4
]
 
3
9.AD.40Eulytine
Bi
 
4
[SiO
 
4
]
 
3
9.AD.45Reidite
Zr[SiO
 
4
]
Related Minerals - Hey's Index Grouping:
14.16.1Uranosilite
UO
 
3
· 7SiO
 
2
14.16.3Soddyite
(UO
 
2
)
 
2
SiO
 
4
·2H
 
2
O
14.16.4Swamboite
UH
 
6
(UO
 
2
)
 
6
(SiO
 
4
)
 
6
·30H
 
2
O
14.16.5Weeksite
K
 
2
(UO
 
2
)
 
2
(Si
 
2
O
 
5
)
 
3
·4H
 
2
O
14.16.6Boltwoodite
(K,Na)(UO
 
2
)[HSiO
 
4
] · 0.5H
 
2
O
14.16.7Natroboltwoodite
(H
 
3
O)(Na,K)UO
 
2
SiO
 
4
·H
 
2
O
14.16.8Cuprosklodowskite
Cu(UO
 
2
)
 
2
[HSiO
 
4
]
 
2
· 6H
 
2
O
14.16.9Sklodowskite
Mg(UO
 
2
)
 
2
[HSiO
 
4
]
 
2
· 5H
 
2
O
14.16.10Uranophane
Ca(UO
 
2
)
 
2
[HSiO
 
4
]
 
2
· 5H
 
2
O
14.16.11β-Uranophane
Ca(UO
 
2
)
 
2
[HSiO
 
4
]
 
2
· 5H
 
2
O
14.16.12Haiweeite
Ca(UO
 
2
)
 
2
[Si
 
5
O
 
12
(OH)
 
2
]·4.5H
 
2
O
14.16.13Metahaiweeite
Ca(UO
 
2
)
 
2
Si
 
6
O
 
15
·nH
 
2
O
14.16.14Thorogummite
(Th,U)[(OH)
 
4x
|(SiO
 
4
)
 
1-x
]
14.16.15Steacyite
([ ],K)(Na,Ca)
 
2
(Th,U)[Si
 
8
O
 
20
]
14.16.16Ekanite
(Ca,Fe
2+
 
,Pb)
 
2
(Th,U)[Si
 
8
O
 
20
]
14.16.17Kasolite
Pb(UO
 
2
)[SiO
 
4
] · H
 
2
O
14.16.18 Orlite
Pb
 
3
(UO
 
2
)
 
3
(Si
 
2
O
 
7
)
 
2
·6H
 
2
O
14.16.19Oursinite
(Co,Mg)(UO
 
2
)
 
2
[HSiO
 
4
]
 
2
· 6H
 
2
O

Other Names for Coffinite

German names:
Coffinit
Russian names:
Коффинит
Spanish names:
Coffinita

Other Information

Health Warning:No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

References for Coffinite

Reference List:American Mineralogist: 41: 675-688.

Internet Links for Coffinite

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  • Raman and XRD data at RRUFF project
  • American Mineralogist Crystal Structure Database
  • Search for Coffinite in the Natural History Museum (London) online catalogue
  • Coffinite details from Handbook of Mineralogy (PDF)
  • Mineral Dealers:
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    Localities for Coffinite

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