The borate carbonates are mixed anion compounds containing both borate and carbonate ions. Compared to mixed anion compounds containing halides, these are quite rare. They are hard to make, requiring higher temperatures, which are likely to decompose carbonate to carbon dioxide. The reason for the difficulty of formation is that when entering a crystal lattice, the anions have to be correctly located, and correctly oriented. They are also known as carbonatoborates or borocarbonates. Although these compounds have been termed carboborate, that word also refers to the C=B=C5− anion, or CB11H12− anion. This last anion should be called 1-carba-closo-dodecaborate or monocarba-closo-dodecaborate. Carboborate can also refer to compounds with anions that have common oxygen between the borate and carbon. These compounds will also be listed in the table.

Some borate carbonates have additional different anions and can be borate carbonate halides or borate carbonate nitrites.

List chemical formulamwcrystal system space groupunit cellvolumedensitycommentreferencesBoron hydrogencarbonateB[μ-H(CO3)2]monoclinicC2 Z = 2 a = 6.997 b = 3.868 c = 5.0197 β = 101.14°133.3at 20 GPaQilianshaniteNaHCO3 · H3BO3 · 2H2Omonoclinica = 16.11 Å, b = 6.92 Å, c = 6.73 Å β = 100.46°1.635Biaxial (-) nα = 1.351 nβ = 1.459 nγ = 1.486 2V: 50°

Max birefringence δ = 0.135CanavesiteMg2(HBO3)(CO3) · 5H2Omonoclinica = 23.49(2) Å, b = 6.16(6) Å, c = 21.91(2) Å β = 114.91(9)° Z=12?1.790Biaxial (+) nα = 1.485 nβ = 1.494 nγ = 1.505 2V: 86°

Max birefringence: δ = 0.020Potassium bis(carbonato)borate hydrateK[B(CO2-μ-O-CO2)2]·2H2OorthorhombicAba2a=11.058 b=11.169 c=9.0504 Z=41117.8spiro at boronNaK15[B4O5(OH)4]6(NO2)2(CO3)·7H2O2035.26hexagonalP2ca=11.1399 c=30.495 Z=23277.32.062K9[B4O5(OH)4]3(CO3)OH⋅7 H2O1128.82hexagonalP2ca=11.207 c=17.193 Z=21870.22.005K9[B4O5(OH)4]3(CO3)Cl·7H2O1147.29hexagonalP2ca=11.219 c=17.079 Z=21861.82.047K9[B4O5(OH)4]3(CO3)Br·7H2O1191.75hexagonalP2ca=11.243 c=17.132 Z=21875.42.110K9[B4O5(OH)4]3(CO3)I⋅7 H2O1238.74hexagonalP2ca=11.234 c=17.158 Z=21875.22.194Ca4(Ca0.7Na0.3)3(Na0.7□ 0.3)Li5[B t12BΔ10O36(O,OH)6](CO3)(OH) · (OH,H2O)R3a=8.99 c=35.91 Z=325132.62ChiyokoiteCa3Si(CO3){[B(OH)4]0.5(AsO3)0.5}(OH)6 · 12H2OhexagonalP63a = 11.0119, c = 10.52521,105.31CarboboriteCa2Mg[B(OH)4]2(CO3)2 · 4H2Omonoclinica = 18.59 Å, b = 6.68 Å, c = 11.32 Å β = 91.68°Biaxial (-) nα = 1.507 nβ = 1.546 nγ = 1.569 Max Birefringence: δ = 0.062BorcariteCa4MgB4O5(OH)6(CO3)2monoclinicC2/ma=17.840 b=8.380 c=4.445 β =102.04649.9062.790Biaxial (-) nα = 1.590 nβ = 1.651 nγ = 1.657

2V: 30°

Max birefringence: δ = 0.067SakhaiteCa3Mg(BO3)2(CO3)2.(H2O)0.36isometricFdma = 14.685 Z=43166.8Ca12Mg4(BO3)7(CO3)4(OH)Cl.H2OFdHarkeriteCa12Mg4Al(BO3)3(SiO4)4(CO3)5 · H2OtrigonalRma = 18.131 Å α = 33.46°1614Uniaxial nα = 1.649 - 1.653 nβ = 1.649 - 1.653ImayoshiiteCa3Al(CO3)[B(OH)4](OH)6 · 12H2OhexagonalP63a = 11.026, c = 10.6051,1171.79Uniaxial (-) nω = 1.497(2) nε = 1.470(2) Max birefringence δ = 0.027GaudefroyiteCa4Mn3O3(BO3)3CO3hexagonalP63/ma = 10.6 Å, c = 5.9 Å5743.529black

Uniaxial (+) nω = 1.805 - 1.810 nε = 2.015 - 2.020

Max Birefringence:δ = 0.210NumanoiteCa4Cu(B4O6(OH)6)(CO3)2monoclinicC2/ma = 17.794 Å, b = 8.381 Å, c = 4.4494 Å β = 102.42° Z=2bluish green Biaxial (-) nα=1.618 nβ=1.658 nγ=1.672

2V: 60°

Max birefringence: δ = 0.054Rb9[B4O5(OH)4]3(CO3)Cl⋅7 H2O1564.59hexagonalP2ca=11.325 c=17.181 Z=21908.32.502Rb9[B4O5(OH)4]3(CO3)Br⋅7 H2O1609.08hexagonalP2ca=11.482 c=17.463 Z=21993.92.680Rb9[B4O5(OH)4]3(CO3)I⋅7 H2O1656.07hexagonalP2ca=11.451 c=17.476 Z=21984.52.771NaRb3B6O9(OH)3(HCO3)monoclinic P21a = 8.988 Å, b = 8.889 Å, c = 10.068 Å, and β = 114.6°Sr5(CO3)2(BO3)2orthorhombicPnmaa = 7.387 b = 16.556 c = 8.971 Z = 4UV cut off 190 nmSr2CuO2(CO3)0.85(BO3)0.15ISr(Na0.4Sr0.1)Na2[B5O8(OH)2] · (CO3)1 − xB2/bMoydite-(Y)Y[B(OH)4](CO3)orthorhombicK6[Cd2(CO3)2(B12O18)(OH)6]1099.19orthorhombicPnnma=13.0603 b=9.1059 c=12.3860 Z=21473.02.478colorlessRb6[Cd2(CO3)2(B12O18)(OH)6]1377.41orthorhombicPnnma=13.3484 b=9.2665 c=12.4946 Z=21545.52.960colorlessBa2(BO3)1-x(CO3)xClx x=0.1Pm1Ba3[B6O10(OH)2](CO3)730.905monoclinica=6.5351, b=8.3455, c =11.3489, and β = 98.9568° Z=2611.43.970Ba5(CO3)2(BO3)2924.34orthorhombicPnmaa=7.923 b=17.508 c=9.114 Z=41268.44.84Ba4Sr(CO3)2(BO3)2874.63orthorhombicPnmaa=7.731 b=17.349 c=9.048 Z=41213.67.787Ba6[B12O21(OH)2](CO3)21443.80monoclinica =6.5485, b = 19.361, c = 18.120, and β = 90.893° Z=42297.04.175Li9BaB15O27(CO3)P1ca=8.860, c=15.148Ba3(BO3)(CO3)F549.84 trigonalRa=10.1799 c=18.530 Z=9 1663.04.941Pb7O(OH)3(CO3)3(BO3)1756.19hexagonalP63/mca=10.519 c=8.90 Z=28536.839SHG 4.5×KDPMereheaditePb47O24(OH)13Cl25(BO3)2(CO3)monoclinicCma = 17.372, b = 27.942, c = 10.6661, β = 93.152o5169.6Britvinite[Pb7(OH)3F(BO3)2(CO3)][Mg4.5(OH)3(Si5O14)]triclinicP1a = 9.3409, b = 9.3579, c = 18.833 α = 80.365°, β = 75.816°, γ = 59.870° Z=21378.75.51Biaxial (-) nα = 1.896 nβ = 1.903 nγ = 1.903

2V 20°

Max birefringence δ = 0.007RoymilleritePb24Mg9(Si10O28)(CO3)10(BO3)(SiO4)(OH)13O5triclinicPa = 9.316, b = 9.316, c = 26.463 α = 83.295°, β = 83.308°, γ = 60.023° Z=11971.25.973Biaxial (-) nα = 1.860 nβ = 1.940 nγ = 1.940 2V 5°

Max birefringence δ = 0.080

References