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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.B: Carbonates with additional anions, without water


5.BA. With cations only in tetrahedral [4] or only in tetragonal pyramidal [5] coordination
 
5.BA.005. Azurite
 
Azurite Cu3(CO3)2(OH)2 mon., P21/c FOTO A

Azurite: with CuO5 tetragonal pyramids.



 
 
5.BB. With cations in tetrahedral + other coordination
 
5.BB.005. Hydrozincite-Aurichalcite group
 
Hydrozincite Zn5(CO3)2(OH)6 mon., C2/m FOTO G
Aurichalcite (Zn,Cu)5(CO3)2(OH)6 mon., P21/m FOTO G

Hydrozincite: cations in tetrahedral and octahedral coordination. Layers of edge-sharing octahedra, every fourth octahedral position is not occupied. On the non-occupied positions to both sides of the layer a tetrahedra is placed.


 
5.BB.010. Loseyite group
 
Loseyite (Mn,Mg)4Zn3(CO3)2(OH)10 mon., C2/c G
Sclarite (Zn,Mg,Mn)4Zn3(CO3)2(OH)10 mon., C2/m IMA 1988-026

Sclarite: framework of cations in tetrahedral and octahedral coordination. The octahedra share edges and corners (Grice & Dunn, 1989, Am. Min. 74, 1355-1359). Loseyite is isostructural.



 
 
5.BC. With cations only in octahedral coordination
 
5.BC.005. Holdawayite
 
Holdawayite Mn6(CO3)2(OH)7(Cl,OH) mon., C2/m IMA 1986-001

Holdawayite: a framework of edge- and corner-sharing octahedra. (Cl,OH) is situated in large tunnels running parallel b.


 
5.BC.010. Dawsonite
 
Dawsonite NaAl(CO3)(OH)2 orth., Imam FOTO G

Dawsonite: AlO2(OH)4 octahedra and distorted NaO4(OH)2 octahedra (Frueh & Golightly, 1967, Can. Min. 9, 51-56).


 
5.BC.015. Barentsite
 
Barentsite Na7Al(CO3)2(HCO3)2F4 tric., P1 (ps.-hex.) IMA 1982-101

Barentsite: layers of edge-sharing Al(O,F)6 octahedra and distorted Na(O,F)6 octahedra parallel (001), the layers are connected by distorted Na(O,F)6 octahedra.



 
 
5.BD. With cations in octahedral + other coordination
 
5.BD.005. Malachite group
 
Pokrovskite Mg2(CO3)(OH)2 mon., P21/a IMA 1982-054
Chukanovite Fe2(CO3)(OH)2 mon., P21/a FOTO IMA 2005-039
Perchiazziite Co2(CO3)(OH)2 mon., P21/a IMA 2023-013
Malachite Cu2(CO3)(OH)2 mon., P21/a FOTO G
Mcguinnessite CuMg(CO3)(OH)2 mon., P21/a IMA 1977-027
Kolwezite CuCo(CO3)(OH)2 mon., P21/a FOTO IMA 1979-017
Glaukosphaerite CuNi(CO3)(OH)2 mon., P21/a FOTO IMA 1972-028
Rosasite CuZn(CO3)(OH)2 mon., P21/a G
Parádsasvárite Zn2(CO3)(OH)2 mon., P21/a IMA 2012-077
Nullaginite Ni2(CO3)(OH)2 mon., P21/m IMA 1978-011
Zincrosasite (Zn,Cu)2(CO3)(OH)2 mon. Q

Malachite: with chains of edge-sharing CuO6 octahedra and CuO5 tetragonal pyramides.


 
5.BD.010. Tunisite
 
Tunisite NaCa2Al4(CO3)4(OH)8Cl tetr., P4/nmm FOTO IMA 1967-038

Tunisite: layers of edge- and corner-sharing AlO6 octahedra, alternating with layers Ca in 10-fold coordination, Na(O4Cl) tetragonal pyramids and carbonate groups. The pyramides with apical chlorine point in the octahedral layer.


 
5.BD.015. Sabinaite
 
Sabinaite Na4TiZr2(CO3)4O4 mon., C2/c IMA 1978-071

Sabinaite: Ti in octadedral, Zr in 7-fold (pentagonal dipyramides) and Na in 6- and 8-fold coordination.


 
5.BD.020. Rouvilleite
 
Rouvilleite Na3Ca(Mn,Ca)(CO3)3F mon., Cc IMA 1989-050

Rouvilleite: Na in distorted octahedral and 7-fold coordination, Mn/Ca is in irregular 6- to 7-fold (distance 2.235 - 2.555 or 2.757 Å) and Ca in 7-fold coordination (Yamnova et al., 1991, Soviet Physics - Crystallography 36, 14-16).



 
 
5.BE. With cations in 7- to 9-fold coordination: cations (Pb, Bi) with stereochemically active lone electron pairs
 
5.BE.005. Shannonite
 
Shannonite Pb2(CO3)O orth., P212121 (?) IMA 1993-053

Shannonite: Pb in irregular 7-fold and 8-fold coordination. The coordination polyhedra are strongly distorted due to the effect of s2 lone electron pairs on the Pb2+ cations (Krivovichev & Burns, 2000, Min. Mag. 64, 1063-1068).


 
5.BE.010. Grootfonteinite
 
Grootfonteinite Pb3(CO3)2O hex., P63mc IMA 2015-051

Grootfonteinite: the structure is formed by layered blocks composed of three sheets [PbCO3][PbO][PbCO3]. The composition of the [PbO] sheet is idealized, the real composition is [(Pb0.7Na0.3)(O0.7(OH)0.3]. The stereochemically active 6s2 lone electron pairs of the two Pb atoms are located in between the blocks, similar to the structure of litharge. Pb is in a 6 + 1 coordination with 6 oxygen (distance of ca. 2.7 Å) in an equatorial plane and one oxygen in a short bond (2.2 Å) perpendicular to one side of the plane, and in a 9-fold coordination around a split position, forming a tricapped trigonal prism. At the second position, a part of the Pb is replaced by Na. The structure is related to the structures of hydrocerussite and abellaite (Siidra et al., 2018, Eur. J. Min. 30, 383-391).


 
5.BE.015. Hydrocerussite
 
Hydrocerussite Pb3(CO3)2(OH)2 trig., P31 FOTO G

Hydrocerussite: the structure is formed by layered blocks composed of three sheets [PbCO3][Pb(OH)2][PbCO3] (Siidra et al., 2018, Eur. J. Min. 30, 383-391).


 
5.BE.020. Plumbonacrite
 
Plumbonacrite Pb5(CO3)3(OH)2O hex., P61/mcm G


 
5.BE.025. Somersetite
 
Somersetite Pb8(CO3)5(OH)2O2 trig., P31c IMA 2017-024

Somersetite: layered structure of alternating blocks of electroneutral plumbonacrite-type [Pb5O(OH)2(CO3)3] and hydrocerussite-type [Pb3(OH)2(CO3)2], separated by stereochemically active lone electron pairs on Pb2+ (Siidra et al., 2018, Min. Mag.).


 
5.BE.030. Abellaite
 
Abellaite NaPb2(CO3)2(OH) hex., P63mc IMA 2014-111

Abellait: the structure is formed by layered blocks composed of three sheets [PbCO3][Na(OH)][PbCO3] (Ibáñez-Insa et al., 2017, Eur. J. Min 10; Siidra et al., 2018, Eur. J. Min. 30, 383-391).


 
5.BE.035. Phosgenite
 
Phosgenite Pb2(CO3)Cl2 tetr., P4/mbm FOTO G

Phosgenite: Pb in 4 O + 5 Cl coordination, forming a strongly deformed monocapped square antiprism. The Pb-O bond lengths showing an average of 2.598 Å and the Pb-Cl of 3.160 Å (Giuseppetti & Tadini, 1974, Tscherm. Min. Petr. Mitt. 21, 101-109).


 
5.BE.040. Bismutite
 
Bismutite Bi2O2(CO3) tetr., I4/mmm FOTO G

Bismutite: layered structure with alternating Bi-O and carbonate layers. Bi(1) in 8-fold (4 + 4) coordination, forming a square antiprism compressed along [001], with bond lenghts around 2.4 Å and 2.842 Å. The compression and the unequal bond-lengths are a consequence of the stereoactive lonepair of electrons associated with Bi3+ ions. Bi(2) has also 8-fold coordination, in a truncated tetrasphenoid. The bond lenghts are shorter (2.23 and 2.67 Å), indicating that the stereoactive lone-pair of electrons are more involved in bonding (Grice, 2002, Can. Min. 40, 693-698).


 
5.BE.045. Kettnerite
 
Kettnerite CaBiO(CO3)F orth., Pmmn FOTO G

Kettnerite: layered structure with a sequence of Bi-O, carbonate, CaF, carbonate layers. The structure is related to the bismutite structure.


 
5.BE.050. Beyerite
 
Beyerite CaBi2O2(CO3)2 tetr., I4/mmm FOTO G



 
 
5.BF. With cations (Na, Ca, Ba, REE) in 6- to 12-fold coordination to O and F
 
5.BF.005. Brenkite
 
Brenkite Ca2(CO3)F2 orth., Pbcn FOTO IMA 1977-036

Brenkite: Ca in irregular coordination with four F and three O, with average Ca-F distances of 2.388 Å and Ca-O distances of 2.426 Å (Leufer & Tillmanns, 1980, Tschermaks min. petr. Mitt. 27, 261-266).


 
5.BF.010. Podlesnoite
 
Podlesnoite Ca2Ba(CO3)2F2 orth., Cmcm IMA 2006-033

Podlesnoite: the structure shows a honeycomb-like framework of columns of edge-sharing CaO6F2 polyhedra stretched parallel to the c axis. Distances of Ca to O/F ranging from 2.2912 to 2.4883 Å. Ba is in 10-fold coordination and forms BaO6F4 polyhedra (distances Ba to O/F from 2.771 to 2.915(2) Å. The CO3 groups are oriented parallel to the ac plane. The structure is slightly related to aragonite (Zubkova et al., 2009, Z. Krist. 222).


 
5.BF.015. Arisite group
 
Arisite-(La) NaLa2(CO3)3-xF1+2x hex., P6m2 IMA 2009-019
Arisite-(Ce) NaCe2(CO3)3-xF1+2x hex., P6m2 IMA 2009-013

Arisite: Na in 6-fold (trigonal prism), REE in 10-fold (9 O + 1 F) coordination.


 
5.BF.020. Cordylite group
 
Cordylite-(La) NaCaBa2La3Sr(CO3)8F2 hex., P63/mmc IMA 2010-058
Cordylite-(Ce) (Na,Ca)BaCe2(CO3)4(F,O) hex., P63/mmc FOTO A
Lukechangite-(Ce) Na3Ce2(CO3)4F hex., P63/mmc IMA 1996-033

Cordylite: (Na/Ca) in 6-fold (trigonal prism), REE in 10-fold and Ba in 12-fold (hexagonal prism) coordination.


 
5.BF.025. Horváthite
 
Horváthite-(Y) NaY(CO3)F2 orth., Pmcn FOTO IMA 1996-032

Horváthite-(Y): with NaO3F4 and YO4F4 polyhedra (Grice & Chao, 1997, Can. Min. 35, 743-749).


 
5.BF.030. Bastnäsite group (Bastnäsite polysomatic series)
 
Bastnäsite-(Y) Y(CO3)F hex., P62c A
Bastnäsite-(La) La(CO3)F hex., P62c Rn
Bastnäsite-(Ce) Ce(CO3)F hex., P62c FOTO Rn
Bastnäsite-(Nd) Nd(CO3)F hex., P62c IMA 2011-062
Hydroxylbastnäsite-(La) La(CO3)(OH) hex., P6 IMA 2021-001
Hydroxylbastnäsite-(Ce) Ce(CO3)(OH) hex., P62c (?) Rn
Hydroxylbastnäsite-(Nd) Nd(CO3)(OH) hex., P62c (?) IMA 1984-060, Rn
Thorbastnäsite (Ca,Ce)Th(CO3)2F2 hex., P62c A

Bastnäsite: the structure is composed of (CeF) and (CO3) layers parallel (0001) in a ratio 1 : 1. Ce is coordinated in CeO6F3 polyhedra with three Ce-F bonds within the (CeF) layer (2.403 - 2.4157 Å) and six bonds to O of the carbonate groups (2.542 - 2.591 Å distance) (Ni et al., 1993, Am. Min. 78, 415-418).


 
5.BF.035. Synchysite group (Bastnäsite polysomatic series)
 
     035 a. Parisite series
Parisite-(La) CaLa2(CO3)3F trig., R3 IMA 2016-031
Parisite-(Ce) CaCe2(CO3)3F trig., R3 FOTO A
 
     035 b. Röntgenite
Röntgenite-(Ce) Ca2Ce3(CO3)5F3 trig., R3 A
 
     035 c. Synchysite series
Synchysite-(Y) CaY(CO3)2F mon., C2/c Rn
Synchysite-(Ce) CaCe(CO3)2F mon., C2/c FOTO A
Synchysite-(Nd) CaNd(CO3)2F orth. (ps.-hex.) IMA 1982-030

The structures of Parisite, Synchysite and Röntgenite are based on the Bastnäsite structure. Additionally to the (CeF) and (CO3) layers, (Ca) layers are present, with different ratios of the three layers. The minerals form a polysomatic series with the general formula [REE(CO3)F]m [CaREE(CO3)2F]n, with Bastnäsite m=1, n=0, Parisite m=1, n=1, Röntgenite m=1, n=2 and Synchysite m=0, n=1.
Ca is in 8-fold coordination (2.34 - 2.85 Å distance). Different polytypes are possible (Ni et al., 2000, Am. Min. 85, 251-258).


 
5.BF.040. Qaqarssukite
 
Qaqarssukite-(Ce) BaCe(CO3)2F trig., P3c1 IMA 2004-019

Qaqarssukite-(Ce) has a layered structure related to that of Synchysite-(Ce), composed of three chemically distinct layers parallel to (0001): (1) carbonate groups oriented perpendicular to the layering, (2) a layer of Ce-O-F polyhedra, and (3) a layer of Ba-O-F polyhedra. Ce is coordinated in CeO6F3 polyhedra, Ba in BaO9F and BaO12 polyhedra (Grice et al., 2006, Can. Min. 44, 1137-1146).


 
5.BF.045. Huanghoite
 
Huanghoite-(Ce) BaCe(CO3)2F trig., R3m A

Huanghoite-(Ce): with CeO9F polyhedra forming layers perpendicular to (001).


 
5.BF.050. Kukharenkoite group
 
Kukharenkoite-(Ce) Ba2Ce(CO3)3F mon., P21/c FOTO IMA 1995-040
Kukharenkoite-(La) Ba2La(CO3)3F mon., P21/c IMA 2002-019

Kukharenkoite: Ba in 10-fold coordination (7 x O and 3 x F with distances Ba to O/F ranging from 2.717 to 2.875 Å) and in 11-fold (or 10 + 1) coordination with O with distances 2.659 and 2.835 to 2.984 Å. REE in 10-fold coordination (9 x O and 1 x F) with distances of the central atom to O/F 2.434 to 2.738 Å. The structure can also be described as having F-centered [FCeBa3] tetrahedra, linked through shared edges to form double chains [FCeBa] along the b axis (Krivovichev et al., 1998, Can. Min. 36, 809-815).


 
5.BF.055. Cebaite
 
Cebaite-(Ce) Ba3Ce2(CO3)5F2 mon., C2/m A

Cebaite-(Ce): with CeO9F polyhedra forming double infinite chains.



 
 
5.BG. Carbonates with additional tetrahedral anions: SO4, PO4, SiO4
 
5.BG.005. Brianyoungite
 
Brianyoungite Zn12(CO3)3(SO4)(OH)16 orth. or mon. FOTO IMA 1991-053


 
5.BG.010. Northupite group
 
Northupite Na6Mg2(CO3)4Cl2 cub., Fd3 G
Tychite Na6Mg2(CO3)4(SO4) cub., Fd3 G
Manganotychite Na6Mn2(CO3)4(SO4) cub., Fd3 IMA 1989-039
Ferrotychite Na6Fe2(CO3)4(SO4) cub., Fd3 IMA 1980-050


 
5.BG.015. Leadhillite group
 
Leadhillite Pb4(CO3)2(SO4)2(OH)2 mon., P21/a G
Macphersonite Pb4(CO3)2(SO4)2(OH)2 orth., Pcab IMA 1982-105
Susannite Pb4(CO3)2(SO4)2(OH)2 trig., P3 G


 
5.BG.020. Philolithite
 
Philolithite Pb12Mn7(CO3)4(SO4)Cl4O6(OH)12 tetr., P42/nnm IMA 1996-020


 
5.BG.025. Reederite
 
Reederite-(Y) (Na,Mn)15Y2(CO3)9(SO3F)Cl hex., P6 IMA 1994-012


 
5.BG.030. Mineevite
 
Mineevite-(Y) BaNa25Y2(CO3)11(HCO3)4(SO4)2F2Cl hex., P63/m IMA 1991-048


 
5.BG.035. Bradleyite group
 
Bradleyite Na3Mg(CO3)(PO4) mon., P21/m G
Sidorenkite Na3Mn(CO3)(PO4) mon., P21/m FOTO IMA 1978-013
Bonshtedtite Na3Fe(CO3)(PO4) mon., P21/m IMA 1981-026a
Crawfordite Na3Sr(CO3)(PO4) mon., P21 IMA 1993-030


 
5.BG.040. Daqingshanite
 
Daqingshanite-(Ce) (Sr,Ca,Ba)3Ce(CO3)3(PO4) trig., R3m IMA 1981-063


 
5.BG.045. Defernite
 
Defernite Ca6(CO3)1.5(Si2O7)0.25(OH)7(Cl0.5(H2O)0.5) orth., Pnam FOTO IMA 1978-057





 
 

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.B: Carbonates with additional anions, without water" completely re-arranged compared to the chemical classification in Strunz 9. The subdivision is based now on structural aspects, the coordination polyhedra, corresponding roughly to the cation size (from smaller to larger cations): 5.BA. With cations only in tetrahedral [4] or only in tetragonal pyramidal [5] coordination; 4.BB. With cations in tetrahedral + other coordination; 5.BC. With cations only in octahedral coordination; 5.BD. With cations in octahedral + other coordination; 5.BE. With cations in 7- to 9-fold coordination: cations (Pb, Bi) with stereochemically active lone electron pairs; 5.BF. With cations (Ca, Ba, REE) in 7- to 12-fold coordination to O and F; 5.BG. Carbonates with additional tetrahedral anions: SO4, PO4, SiO4.
Further classification:
5.BA. With cations only in tetrahedral [4] or only in tetragonal pyramidal [5] coordination: Only one mineral.
5.BB. With cations in tetrahedral + other coordination: With cations in tetrahedral and octahedral coordination, only 2 groups.
5.BC. With cations only in octahedral coordination: Mainly medium-sized cations in octahedral coordination; large cations in octahedral coordination.
5.BD. With cations in octahedral + other coordination: Medium-sized cations in octahedral + other cations in other coordination sorted according to increasing coordination number; large cations in octahedral + other cations in other coordination.
5.BE. With cations in 7- to 9-fold coordination: cations (Pb, Bi) with stereochemically active lone electron pairs: Pb carbonates; Bi carbonates.
5.BF. With cations (Na, Ca, Ba, REE) in 6- to 12-fold coordination to O and F: Single coordination type, arranged with increasing coordination number; more than one coordination type, arranged with increasing coordination number. Exception: Bastnäsite group placed next to the Synchysite group because of the close structural relation.
5.BG. Carbonates with additional tetrahedral anions: SO4, PO4, SiO4: Carbonates with additional SO4; with PO4; with SiO4.


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


© Thomas Witzke (2023)


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