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Coffinite

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Formula:
(U4+,Th)(SiO4)1-x(OH)4x
System:
Tetragonal
Colour:
Black
Hardness:
5 - 6
Name:
named for Reuben Clare Coffin (October 29, 1886-September 10, 1972) for his outstanding geologic studies in southwestern Colorado. Stanolind oil company and consultant to USGS.
This page provides mineralogical data about Coffinite.

Classification of Coffinite

Approved, 'Grandfathered' (first described prior to 1959)
9.AD.30

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
14.16.2

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

General Appearance of Type Material:
fine grained
Geological Setting of Type Material:
unoxidized uranium deposit

Occurrences of Coffinite

Geological Setting:
unoxidized uranium deposits

Physical Properties of Coffinite

Adamantine
Colour:
Black
Comment:
transmitted light the smaller particles of coffinite-bearing material are pale brown to very dark brown on thin edges;
Hardness (Mohs):
5 - 6
Tenacity:
Brittle
Fracture:
Irregular/Uneven, Sub-Conchoidal
Density:
5.1 g/cm3 (Measured)    

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
Max Birefringence:
δ = 1.730
Image shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
Surface Relief:
High

Chemical Properties of Coffinite

Formula:
(U4+,Th)(SiO4)1-x(OH)4x
All elements listed in formula:
Common Impurities:
Al,Fe,As,V,Pb

Relationship of Coffinite to other Species

Common Associates:
9.AD.05LarniteCa2SiO4
9.AD.10Calcio-olivineCa2SiO4
9.AD.15MerwiniteCa3Mg(SiO4)2
9.AD.20BredigiteCa7Mg(SiO4)4
9.AD.25AndraditeCa3Fe23+(SiO4)3
9.AD.25AlmandineFe32+Al2(SiO4)3
9.AD.25Calderite(Mn2+,Ca)3(Fe3+,Al)2(SiO4)3
9.AD.25GoldmaniteCa3V23+(SiO4)3
9.AD.25GrossularCa3Al2(SiO4)3
9.AD.25HenritermieriteCa3(Mn3+,Al)2(SiO4)2(OH)4
9.AD.25HibschiteCa3Al2(SiO4)3-x(OH)4x
9.AD.25HydroandraditeCa3Fe23+(SiO4)3-x(OH)4x
9.AD.25KatoiteCa3Al2(SiO4)3-x(OH)4x
9.AD.25KimzeyiteCa3(Zr,Ti)2((Si,Al,Fe3+)O4)3
9.AD.25KnorringiteMg3Cr2(SiO4)3
9.AD.25MajoriteMg3(Fe2+,Si,Al)2(SiO4)3
9.AD.25MorimotoiteCa3(Ti,Fe2+,Fe3+)2((Si,Fe3+)O4)3
9.AD.25PyropeMg3Al2(SiO4)3
9.AD.25SchorlomiteCa3(Ti,Fe3+)2((Si,Fe3+)O4)3
9.AD.25SpessartineMn32+Al2(SiO4)3
9.AD.25UvaroviteCa3Cr2(SiO4)3
9.AD.25Wadalite(Ca,Mg)6(Al,Fe3+)4((Si,Al)O4)3O4Cl3
9.AD.25HoltstamiteCa3(Al,Mn3+)2(SiO4)2(OH)4
9.AD.25KerimasiteCa3Zr2(SiO4)(Fe3+O4)2
9.AD.25ToturiteCa3Sn2(SiO4)(Fe3+O4)2
9.AD.25Momoiite(Mn2+,Ca)3V23+(SiO4)3
9.AD.25EltyubyuiteCa12Fe103+Si4O32Cl6
9.AD.25HutcheoniteCa3Ti2(SiAl2)O12
9.AD.30HafnonHf(SiO4)
9.AD.30ThoriteTh(SiO4)
9.AD.30ZirconZr(SiO4)
9.AD.30StetinditeCe(SiO4)
9.AD.35HuttoniteThSiO4
9.AD.35Tombarthite-(Y)Y4(Si,H4)4O12-x(OH)4+2x
9.AD.40EulytineBi4(SiO4)3
9.AD.45ReiditeZrSiO4
14.16.1UranosiliteUO3 · 7SiO2
14.16.3Soddyite(UO2)2SiO4 · 2H2O
14.16.4SwamboiteU6+(UO2)6(SiO3OH)6 · 30H2O
14.16.5WeeksiteK2(UO2)2(Si5O13) · 4H2O
14.16.6Boltwoodite(K,Na)(UO2)(SiO3OH) · 1.5H2O
14.16.7NatroboltwooditeNa(UO2)(SiO3OH) · H2O
14.16.8CuprosklodowskiteCu(UO2)2(SiO3OH]2 · 6H2O
14.16.9SklodowskiteMg(UO2)2(SiO3OH)2 · 6H2O
14.16.10UranophaneCa(UO2)2(SiO3OH)2 · 5H2O
14.16.11Uranophane-βCa(UO2)2(SiO3OH)2 · 5H2O
14.16.12HaiweeiteCa(UO2)2[Si5O12(OH)2] · 6H2O
14.16.13MetahaiweeiteCa(UO2)2Si6O15 · nH2O
14.16.15SteacyiteK0.3(Na,Ca)2ThSi8O20
14.16.16EkaniteCa2ThSi8O20
14.16.17KasolitePb(UO2)[SiO4] · H2O
14.16.18OrlitePb3(UO2)3(Si2O7)2 · 6H2O
14.16.19OursiniteCo(UO2)2(SiO3OH)2 · 6H2O

Other Names for Coffinite

Name in Other Languages:
German:Coffinit
Simplified Chinese:水硅铀矿
硅铀矿
铀石
Spanish:Coffinita
Traditional Chinese:水矽鈾礦
矽鈾礦
鈾石

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.
Industrial Uses:
uranium ore

References for Coffinite

Reference List:
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

Internet Links for Coffinite

Localities for Coffinite

map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.
Mineral and/or Locality  
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