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MINERAL CLASSIFICATION / SYSTEMATIK der MINERALE

           based on E.H. Nickel & M.C. Nichols (2009), H. Strunz & E.H. Nickel (2001),
           revised by Thomas Witzke (2023)



5. CARBONATES
(Carbonates, Nitrates)


5.E: Uranylcarbonates


5.EA. With finite clusters of hexagonal UO8 bipyramids: with uranyl tricarbonate [UO2(CO3)3]4- groups or [U2O6(CO3)4]8- groups
 
5.EA.005. Bayleyite
 
Bayleyite Mg2(UO2)(CO3)3·18H2O mon., P21/c G

Bayleyite: the structure consists of isolated uranyl tricarbonate anions [UO2(CO3)3]4-, magnesium hexahydrate octahedra [Mg(H2O)6]2+ and free water molecules (Colmenero et al., 2020, Spectrochim. Acta A)


 
5.EA.010. Swartzite
 
Swartzite CaMg(UO2)(CO3)3·12H2O mon., P21/m G

Swartzite: isolated clusters of the composition Ca(H2O)6[UO2(CO3)3]2-, formed of uranyl tricarbonate anions [UO2(CO3)3]4- and Ca(H2O)6O2 square antiprisms, sharing edges with the uranyl tricarbonate groups. Isolated Mg(H2O)22+ octahedra are linked via a system of hydrogen bonds to the clusters (Mereiter, 1986, N. Jb. Min. Mh., 481-492).


 
5.EA.015. Čejkaite group
 
Čejkaite Na4(UO2)(CO3)3 tric., P1 or P1 IMA 1999-045
Agricolaite K4(UO2)(CO3)3 mon., C2/c IMA 2009-081

Čejkaite: uranyl tricarbonate anions [UO2(CO3)3]4-, Na in octahedral and pentagonal coordination, with oxygen from carbonate groups and apical oxygen from hexagonal UO8 bipyramids (Ondruš et al., 2015, Am. Min. 88, 686-693).


 
5.EA.020. Leószilárdite
 
Leószilárdite Na6Mg(UO2)2(CO3)6·6H2O mon., C2/m IMA 2015-128, Rn

Leószilárdite: uranyl tricarbonate anions [UO2(CO3)3]4-, linked by irregular chains of NaO5(H2O) polyhedra and by three-octahedron units consisting of two Na-centred octahedra that share the opposite faces of a Mg-centred octahedron at the centre, and have the composition Na2MgO12(H2O)4 (Olds et al., 2017, Min. Mag. 81, 1030-1050).


 
5.EA.025. Andersonite
 
Andersonite Na2Ca(UO2)(CO3)3·6H2O trig., R3m FOTO G

Andersonite: uranyl tricarbonate anions [UO2(CO3)3]4- connected to polyhedra with Ca in 7-fold coordination and Na centered distorted octahedra forming together with additional, more distorted NaO2(H2O)4 octahedra (with two splitted water positions) columnar, well-like units with zeolite-like channels in c direction. The channels are occupied by water (Gurzhiy et al., 2018, Minerals 8, 586).


 
5.EA.030. Grimselite
 
Grimselite K3Na(UO2)(CO3)3·H2O hex., P62c IMA 1971-040

Grimselite: uranyl tricarbonate anions [UO2(CO3)3]4- linked into layers via NaO8 hexagonal bipyramids. Each NaO8 polyhedron shares three equatorial edges with (CO3) groups so that one oxygen is shared between the UO8 and NaO8 polyhedra and a carbonate group. The resulting heteropolyhedral layers are stacked along [001]. Adjacent layers are linked by sharing apical oxygen of UO8 and NaO8 hexagonal bipyramids. Voids in the resulting heteropolyhedral framework contain K cations and H2O groups (Li & Burns, 2001, Can. Min. 39, 1147-1151).


 
5.EA.035. Liebigite
 
Liebigite Ca2(UO2)(CO3)3·11H2O orth., Bba2 FOTO G

Liebigite: uranyl tricarbonate anions [UO2(CO3)3]4-, linked by CaO4(H2O)4 and CaO3(H2O)4 polyhedra to form puckered layers of the composition Ca2(UO2)(CO3)3·11H2O. The layers are interconnected by hydrogen bonds, both directly and via 3 interlayer water molecules per formula unit (Mereiter, 1982, Z. Krist, 30, 277-288).


 
5.EA.040. Markeyite group
 
Markeyite Ca9(UO2)4(CO3)13·28H2O orth., Pmmn IMA 2016-090
Natromarkeyite Na2Ca8(UO2)4(CO3)13·27H2O orth., Pmmn IMA 2018-152


 
5.EA.045. Pseudomarkeyite
 
Pseudomarkeyite Ca8(UO2)4(CO3)12·21H2O mon., P21/m IMA 2018-114


 
5.EA.050. Paramarkeyite
 
Paramarkeyite Ca2(UO2)(CO3)3·5H2O mon., P21/n IMA 2021-024


 
5.EA.055. Shabaite
 
Shabaite-(Nd) CaNd2[(UO2)(CO3)3](CO3)2·10.5H2O tric., P1, ps.-mon. IMA 1988-005

Shabaite-(Nd): new formula and crystal system according to a structure determination. The structure contains uranyl tricarbonate anions [UO2(CO3)3]4-, Ca polyhedra and infinite layers of Nd polyhedra. The layers are oriented perpendicular to c (Plášil & Škoda, 2017, J. of Geosciences 62, 97-105).


 
5.EA.060. Línekite
 
Línekite K2Ca3(UO2)2(CO3)6·7H2O orth., Pnnm IMA 2012-066

Línekite: uranyl tricarbonate anions [UO2(CO3)3]4- and Ca centered polyhedra forming layers stacked along (100). Four uranyl tricarbonate groups are connected by Ca polyhedra forming a "paddlewheel" motive. Each uranyl tricarbonate group belongs to two paddlewheels (Plášil et al., 2017, J. of Geosciences 62, 201-213).


 
5.EA.065. Braunerite
 
Braunerite K2Ca(UO2)(CO3)3·6H2O mon., P21/c IMA 2015-123


 
5.EA.070. Albrechtschraufite
 
Albrechtschraufite Ca4Mg(UO2)2(CO3)6F2·17H2O tric., P1 IMA 1983-078

Albrechtschraufite: uranyl tricarbonate anions [UO2(CO3)3]4-, MgF2O3(H2O) octahedra, CaFO6, CaF2O2(H2O)4, CaFO3(H2O)4 and CaO2(H2O)6 polyhedra. Four uranyl tricarbonate groups are connected by Ca polyhedra forming a "paddlewheel" motive. The crystal structure is built up from MgCa3F2[UO2(CO3)3]·8H2O layers parallel to (001) which are linked by Ca[UO2(CO3)3]·5H2O moieties into a framework. Five additional water molecules are located in voids of the framework (Mereiter, 2012, Miner. Petrol. 107, 179-188).


 
5.EA.075. Paddlewheelite
 
Paddlewheelite MgCa5Cu2(UO2)4(CO3)12·33H2O mon., Pc IMA 2017-098

Paddlewheelite: One of the minerals with the most complex crystal structure. Four uranyl tricarbonate anions [UO2(CO3)3]4-, linked by CaO8 cubes and CuO5 to a "paddlewheel" motive. The paddlewheels are connected by Ca polyhedra in 7- and 8-fold coordination. Mg is in octahedral coordination in pores petween the paddlewheels (Olds et al., 2018, Minerals 8, 511).


 
5.EA.080. Ježekite
 
Ježekite Na8(UO2)(SO4)2(CO3)3·3H2O hex., P62m IMA 2014-079

Ježekite: uranyl tricarbonate anions [UO2(CO3)3]4-, forming with Na cations in 8-fold coordination ordered {Na2[(UO2)(CO3)3]}2- sheets, alternating with a an interlayer with six Na+ ions plus highly disordered sheets of composition {[(SO4)2(H2O)3]}4- (Plášil et al., 2015, J. of Geosciences 60, 259-267).


 
5.EA.085. Schröckingerite
 
Schröckingerite NaCa3(UO2)(SO4)(CO3)3F·10H2O tric., P1 FOTO G

Schröckingerite: the structure contains NaCa3[(UO2)(CO3)3] (SO4)F·6H2O layers built up from uranyl tricarbonate anions [UO2(CO3)3]4-, NaO3(H2O)3 octahedra, three kinds of CaO5F(H2O)2 polyhedra, Ca3F pyramids and Ca-bonded SO4 tetrahedra. The layers are stacked along the c direction and linked by hydrogen bonds, both directly as well as via interlayer H4O molecules (Mereiter, 1986, Tscherm. Min. Petr. Mitt. 35, 1-18).


 
5.EA.090. Pendevilleite-(Y)
 
Pendevilleite-(Y) Mg2Y3Al(UO2)2(CO3)7(OH)6·16H2O tric., P1 IMA 2022-054



 
 
5.EB. With arrangements of uranyl tricarbonate groups [UO2(CO3)3]4- and pentagonal UO7 bipyramids
 
5.EB.005. Meyrowitzite
 
Meyrowitzite Ca(UO2)(CO3)2·5H2O mon., P21/n IMA 2018-039


 
5.EB.010. Ewingite
 
Ewingite Mg8Ca8(UO2)24(CO3)30O4(OH)12·138H2O tetr., I41/acd IMA 2016-012

Ewingite: is regarded as the most complex mineral known at time (Nov. 2023). The structure contains nanometer-scale anionic uranyl carbonate cages that contain 24 uranyl polyhedra, as well as Ca and Mg cations. Water is located in interstitial regions inside and between the cages. The cage contains three building blocks, (1) a trimer of corner-sharing pentagonal UO7 bipyramids, forming a cluster [U3O16], (2) uranyl tricarbonate groups [UO2(CO3)3] and (3) the uranyl ion is coordinated by two carbonate groups and two H2O groups in the equatorial region of a hexagonal bipyramid [UO2(CO3)2(H2O)2] (as in uranyl tricarbonate groups, but one carbonate is replaced by two H2O). Ca and Mg cations are situated inside the cages, but link also the cages (Olds et al., 2017, Geology 45, 1007-1010).



 
 
5.EC. With chains of hexagonal UO8 bipyramids
 
5.EC.005. Widenmannite
 
Widenmannite Pb2(OH)2(UO2)(CO3)2 orth., Pmmn IMA 1974-008

Widenmannite: the ideal structure contains chains of corner-sharing hexagonal UO8 bipyramids. Each bipyramide shares an edge with a carbonate group, a second carbonate group is shared between two bipyramids (can also be described as chains of uranyl tricarbonate groups with an "overlapping" carbonate). The uranyl carbonate chains are interconnected by a network of Pb-O bonds. In the real structure, around 7 % of the U positions in the chains are not occupied, instead a second U centered hexagonal bipyramide connect the chains, accompanied by a vacant Pb site (Plášil et al., 2014, Am. Min. 99, 276-282).



 
 
5.ED. With complex chains of pentagonal UO7 and hexagonal UO8 bipyramids, connected to sheets by carbonate groups or other anion centered polyhedra.
 
5.ED.005. Fontanite
 
Fontanite Ca(UO2)3(CO3)2O2·6H2O mon., P211/n IMA 1991-034

Fontanite: structure is based on the phosphuranylite anion topology. The structure contains chains of two symmetrically distinct uranyl pentagonal bipyramids (forming a dimer), one uranyl hexagonal bipyramid, and two CO3 triangles. The dimers are oriented perpendicular to the chain direction and are connected sharing equatorial edges with hexagonal bipyramids. The CO3 groups occur on either side of the chains, where they share equatorial edges of the uranyl hexagonal bipyramids, and share their third ligand with a uranyl pentagonal bipyramid of an adjacent chain. The arrangement resulting in uranyl carbonate sheets of composition [(UO2)3(CO3)2O2]2-. The Ca2+ cation is located between the sheets, and is coordinated by two O atoms of uranyl ions of adjacent sheets, and six H2O groups Hughes & Burns, 2003, Am. Min. 88, 962-966).


 
5.ED.010. Roubaultite
 
Roubaultite Cu2(UO2)3(CO3)2O2(OH)2·4H2O tric., P1 IMA 1970-030

Roubaultite: structure is based on the phosphuranylite anion topology. Chains of alternating hexagonal bipyramids and dimers of pentagonal bipyramids. The chains are connected to layers via distorted Cu centered octahedra (Ginderow & Cesbron, 1985, Acta Cryst. C41, 654-657).


 
5.ED.015. Bijvoetite-(Y)
 
Bijvoetite-(Y) Y8(UO2)16O8(CO3)16(OH)8·39H2O mon., B1211 IMA 1981-035

Bijvoetite-(Y): pseudo-orthorhombic. Complex chains of pentagonal and hexagonal U centered bipyramids in [100] direction. The chains are connected via irregular REE centered polyhedra to layers parallel (010). A part of the water belongs to the REE polyhedra. Adjacent layers are connected by H bonds only from interlayer water (Li et al., 2000, Can. Min. 38, 153-162).


 
5.ED.020. Kamotoite-(Y)
 
Kamotoite-(Y) Y2(UO2)4O4(CO3)3·14H2O mon., P21/n IMA 1985-051

Kamotoite-(Y): pseudo-orthorhombic supercell, identical to the cell of Bijvoetite-(Y). The crystal structure topology is the same as in Bijvoetite-(Y). It might be that the two minerals are identical (Plášil & Petřiček, 2017, Min. Mag. 81, 653-660).



 
 
5.EE. Structures containing sheets based on tetragonal UO6 and pentagonal UO7 bipyramids
 
5.EE.005. Wyartite
 
Wyartite CaU5+(U6+O2)2(CO3)O4(OH)·7H2O orth., P212121 A

Wyartite: structure is a derivative of the beta-U3O8 topology. The mineral contains layers composed of U6+O7 pentagonal bipyramids and U5+O6 square bipyramids.



 
 
5.EF. Structures containing sheets based on hexagonal UO8 bipyramids
 
5.EF.005. Rutherfordine
 
Rutherfordine (UO2)(CO3) orth., Imm2 A

Rutherfordine: neutral sheets of edge- and corner-sharing (UO8) hexagonal bipyramids and CO3 groups (Finch et al., 1999, Can. Min. 37, 929-938).


 
5.EF.020. Sharpite
 
Sharpite Ca(UO2)3(CO3)4·3H2O orth., Cmcm G

Sharpite: the topology of the sheets is identical to rutherfordine. The structure is based upon infinite Ca2+-uranyl-carbonate sheets with hexagonal bipyramids UO8 and . Ca2+(H2O)3O5. Ca2+ is occupying one of the U6+ positions in the sheets. The sheets are extremely corrugated, stacked perpendicular to b and linked by H-bonds and Van Der Waals interactions, only (Plášil, 2018, Z. Krist. 233, 579-586).



 
 
5.EG. Uranylcarbonates with unknown crystal structure
 
5.EG.005. Urancalcarite
 
Urancalcarite Ca(UO2)3(CO3)(OH)6·3H2O orth., Pbnm or Pbn21 IMA 1983-052

Urancalcarite: crystal structure not known.


 
5.EG.010. Oswaldpeetersite
 
Oswaldpeetersite (UO2)2(CO3)(OH)2·4H2O mon., P21/b IMA 2000-034

Oswaldpeetersite: crystal structure not known.


 
5.EG.015. Blatonite
 
Blatonite (UO2)(CO3)·H2O hex. or trig. IMA 1997-025

Blatonite: crystal structure not known.


 
5.EG.020. Joliotite
 
Joliotite (UO2)(CO3)·2H2O orth., Pmmm IMA 1974-014

Joliotite: crystal structure not known.


 
5.EG.025. Zellerite group
 
Metazellerite Ca(UO2)(CO3)2·3H2O orth., Pmnm or Pmn21 IMA 1965-032
Zellerite Ca(UO2)(CO3)2·5H2O orth., Pmnm or Pmn21 IMA 1965-031

Zellerite and Metazellerite: crystal structure not known.


 
5.EG.030. Voglite
 
Voglite Ca2Cu(UO2)(CO3)4·6H2O mon., P21 or P21/m FOTO A

Voglite: crystal structure not known.


 
5.EG.035. Rabbittite
 
Rabbittite Ca3Mg3(UO2)2(CO3)6(OH)4·18H2O mon. (?) FOTO G

Rabbittite: crystal structure not known. The mineral probably contains Fluorine. Re-study of type material necessary. The ratio of (UO2) : (CO3) = 1 : 3 suggest that the mineral might contain uranyl tricarbonate anions [UO2(CO3)3]4-.


 
5.EG.040. Lepersonnite group
 
Lepersonnite-(Gd) CaGd2(UO2)24(SiO4)4(CO3)8(OH)24·48H2O orth., Pnnm or Pnn2 IMA 1981-036
Lepersonnite-(Nd) Nd4(UO2)24(SiO4)4(CO3)8(OH)28·48H2O orth., Pnnm or Pnm21 IMA 2021-066


 
5.EG.045. Znucalite
 
Znucalite CaZn12(UO2)(CO3)3(OH)22·4H2O tric., P1 or P1 FOTO IMA 1989-033

Crystal structure not published yet, in press. Steciuk, G., Majzlan, J., Rohlícek, J., Skoda, R., Sejkora, J., Plásil, J. (2023): Znucalite, the only known zinc uranyl carbonate: its crystal structure and environmental implications. American Mineralogist, 108, (in press).


 
5.EG.050. Astrocyanite
 
Astrocyanite-(Ce) Cu2Ce2(UO2)(CO3)5(OH)2·1.5H2O hex., P6/mmm FOTO IMA 1989-032

Astrocyanite-(Ce): crystal structure not known.






 
 

G = Grandfathered minerals: original description preceded the establishment of the CNMNC in 1959, and generally regarded as a valid species
A or IMA No. = Minerals approved by the CNMNC
Rd = Redefinition of the mineral approved by the CNMNC
Rn = Renamed with approval by the CNMNC
Q = Questionable mineral



Classification principles:
Subdivision of the Carbonates subclass "5.E: Uranylcarbonates" completely re-arranged compared to the chemical classification in Strunz 9. The subdivision is based now on structural aspects, the arrangement of UOn polyhedra: 5.EA. With finite clusters of hexagonal UO8 bipyramids: with uranyl tricarbonate [UO2(CO3)3]4- groups or [U2O6(CO3)4]8- groups; 5.EB. With arrangements of uranyl tricarbonate groups [UO2(CO3)3]4- and pentagonal UO7 bipyramids; 5.EC. With chains of hexagonal UO8 bipyramids; 5.ED. With complex chains of pentagonal UO7 and hexagonal UO8 bipyramids, connected to sheets by carbonate groups or other anion centered polyhedra; 5.EE. Structures containing sheets based on tetragonal UO6 and pentagonal UO7 bipyramids; 5.EF. Structures containing sheets based on hexagonal UO8 bipyramids; 5.EG. Uranylcarbonates with unknown crystal structure.
Further classification:
5.EA. With finite clusters of hexagonal UO8 bipyramids: with uranyl tricarbonate [UO2(CO3)3]4- groups or [U2O6(CO3)4]8- groups: Sorted according to the arrangement of uranyl tricarbonate (UTC) groups and other cation centered polyhedra. Isolated UTC groups (Bayleyite); isolated clusters of UTC groups with other polyhedra (Swartzite); UTC groups connected by other polyhedra; UTC groups and other polyhedra in layered structures (Liebigite and related minerals, Shabaite-(Nd)); UTC groups arranged in a paddlewheel motive; carbonates with UTC groups and additional tetrahedral anions; with [U2O6(CO3)4]8- groups.
5.EB. With arrangements of uranyl tricarbonate groups [UO2(CO3)3]4- and pentagonal UO7 bipyramids: Only two minerals, arranged with increasing complexity.
5.EC. With chains of hexagonal UO8 bipyramids: Only one mineral.
5.ED. With complex chains of pentagonal UO7 and hexagonal UO8 bipyramids, connected to sheets by carbonate groups or other anion centered polyhedra: Minerals with phosphuranylite sheet topology; minerals with related sheets.
5.EE. Structures containing sheets based on tetragonal UO6 and pentagonal UO7 bipyramids: Only one mineral.
5.EF. Structures containing sheets based on hexagonal UO8 bipyramids: Rutherfordine type sheets and derivative.
5.EG. Uranylcarbonates with unknown crystal structure: Sorted with increasing carbonate content.


To distinguish from classical Strunz numbering, on hierarchical "group" level, a numbering with 3 digits is used, like "5.EA.005. Bayleyite", instead of 2 digits (like "5.EA.05.") in the Strunz system.


Used references:
Burns, P. (2005): U6+ minerals and inorganic compounds: insights into an expanded structural hierarchy of crystal structures. Can. Min. 43, 1839-1894.



© Thomas Witzke (2023)


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