Borate carbonate

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.^[1] They are also known as carbonatoborates or borocarbonates.^[2] Although these compounds have been termed carboborate, that word also refers to the C=B=C⁵⁻ anion, or CB₁₁H₁₂⁻ anion.^[3] This last anion should be called 1-carba-closo-dodecaborate^[4] or monocarba-closo-dodecaborate.^[5]

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

List

	chem	mw	crystal system	space group	unit cell	volume	density	comment	references
Qilianshanite	NaHCO3 · H3BO3 · 2H2O		monoclinic		a = 16.11 Å, b = 6.92 Å, c = 6.73 Å β = 100.46°		1.635	Biaxial (-) nα = 1.351 nβ = 1.459 nγ = 1.486 2V: 50° Max birefringence δ = 0.135	[6]
Canavesite	Mg2(HBO3)(CO3) · 5H2O		monoclinic		a = 23.49(2) Å, b = 6.16(6) Å, c = 21.91(2) Å β = 114.91(9)° Z=12?		1.790	Biaxial (+) nα = 1.485 nβ = 1.494 nγ = 1.505 2V: 86° Max birefringence: δ = 0.020	[7]
Potassium bis(carbonato)borate hydrate	K[B(CO2-μ-O-CO2)2]·2H2O		orthorhombic	Aba2	a=11.058 b=11.169 c=9.0504 Z=4	1117.8		spiro at boron	[8]
	NaK15[B4O5(OH)4]6(NO2)2(CO3)·7H2O	2035.26	hexagonal	P62c	a=11.1399 c=30.495 Z=2	3277.3	2.062		[9]
	K9[B4O5(OH)4]3(CO3)OH⋅7 H2O	1128.82		P62c	a=11.207 c=17.193 Z=2	1870.2	2.005		[10]
	K9[B4O5(OH)4]3(CO3)Cl·7H2O	1147.29	hexagonal	P62c	a=11.219 c=17.079 Z=2	1861.8	2.047		[11]
	K9[B4O5(OH)4]3(CO3)Br·7H2O	1191.75	hexagonal	P62c	a=11.243 c=17.132 Z=2	1875.4	2.110		[11]
	K9[B4O5(OH)4]3(CO3)I⋅7 H2O	1238.74		P62c	a=11.234 c=17.158 Z=2	1875.2	2.194		[10]
	Ca4(Ca0.7Na0.3)3(Na0.7□ 0.3)Li5[B t12BΔ10O36(O,OH)6](CO3)(OH) · (OH,H2O)			R3	a=8.99 c=35.91 Z=3	2513	2.62		[12]
Chiyokoite	Ca3Si(CO3){[B(OH)4]0.5(AsO3)0.5}(OH)6 · 12H2O		hexagonal	P63	a = 11.0119, c = 10.5252	1,105.31			[13]
Carboborite	Ca2Mg[B(OH)4]2(CO3)2 · 4H2O		monoclinic		a = 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 = 0.062	[14]
Borcarite	Ca4MgB4O5(OH)6(CO3)2		monoclinic	C2/m	a=17.840 b=8.380 c=4.445 β =102.04	649.906	2.790	Biaxial (-) nα = 1.590 nβ = 1.651 nγ = 1.657 2V: 30° Max birefringence: δ = 0.067	[1][15]
Sakhaite	Ca3Mg(BO3)2(CO3)2.(H2O)0.36		isometric	Fd3m	a = 14.685 Z=4	3166.8			[1][16]
	Ca12Mg4(BO3)7(CO3)4(OH)Cl.H2O			Fd3					[1]
Harkerite	Ca12Mg4Al(BO3)3(SiO4)4(CO3)5 · H2O		trigonal	R3m	a = 18.131 Å α = 33.46°	1614		Uniaxial nα = 1.649 - 1.653 nβ = 1.649 - 1.653	[17]
Imayoshiite	Ca3Al(CO3)[B(OH)4](OH)6 · 12H2O		hexagonal	P63	a = 11.026, c = 10.605	1,117	1.79	Uniaxial (-) nω = 1.497(2) nε = 1.470(2) Max birefringence δ = 0.027	[18]
Gaudefroyite	Ca4Mn3O3(BO3)3CO3		hexagonal	P63/m	a = 10.6 Å, c = 5.9 Å	574	3.529	black Uniaxial (+) nω = 1.805 - 1.810 nε = 2.015 - 2.020 Max Birefringence:δ = 0.210	[1][19]
Numanoite	Ca4Cu(B4O6(OH)6)(CO3)2		monoclinic	C2/m	a = 17.794 Å, b = 8.381 Å, c = 4.4494 Å β = 102.42° Z=2			bluish green Biaxial (-) nα=1.618 nβ=1.658 nγ=1.672 2V: 60° Max birefringence: δ = 0.054	[20]
	Rb9[B4O5(OH)4]3(CO3)Cl⋅7 H2O	1564.59		P62c	a=11.325 c=17.181 Z=2	1908.3	2.502		[10]
	Rb9[B4O5(OH)4]3(CO3)Br⋅7 H2O	1609.08		P62c	a=11.482 c=17.463 Z=2	1993.9	2.680		[10]
	Rb9[B4O5(OH)4]3(CO3)I⋅7 H2O	1656.07		P62c	a=11.451 c=17.476 Z=2	1984.5	2.771		[10]
	NaRb3B6O9(OH)3(HCO3)		monoclinic	P21	a = 8.988 Å, b = 8.889 Å, c = 10.068 Å, and β = 114.6°				[21]
	Sr5(CO3)2(BO3)2		orthorhombic	Pnma	a = 7.387 b = 16.556 c = 8.971 Z = 4			UV cut off 190 nm	[22]
	Sr2CuO2(CO3)0.85(BO3)0.15			I4					[1]
	Sr(Na0.4Sr0.1)Na2[B5O8(OH)2] · (CO3)1 − x			B2/b					[23]
Moydite-(Y)	Y[B(OH)4](CO3)		orthorhombic						[24]
	K6[Cd2(CO3)2(B12O18)(OH)6]	1099.19	orthorhombic	Pnnm	a=13.0603 b=9.1059 c=12.3860 Z=2	1473.0	2.478	colorless	[25]
	Rb6[Cd2(CO3)2(B12O18)(OH)6]	1377.41	orthorhombic	Pnnm	a=13.3484 b=9.2665 c=12.4946 Z=2	1545.5	2.960	colorless	[25]
	Ba2(BO3)1-x(CO3)xClx x=0.1			P3m1					[1]
	Ba3[B6O10(OH)2](CO3)	730.905	monoclinic		a=6.5351, b=8.3455, c =11.3489, and β = 98.9568° Z=2	611.4	3.970		[26]
	Ba5(CO3)2(BO3)2	924.34	orthorhombic	Pnma	a=7.923 b=17.508 c=9.114 Z=4	1268.4	4.84		[1]
	Ba4Sr(CO3)2(BO3)2	874.63	orthorhombic	Pnma	a=7.731 b=17.349 c=9.048 Z=4	1213.6	7.787		[1]
	Ba6[B12O21(OH)2](CO3)2	1443.80	monoclinic		a =6.5485, b = 19.361, c = 18.120, and β = 90.893° Z=4	2297.0	4.175		[26]
	Li9BaB15O27(CO3)			P31c	a=8.860, c=15.148				[1][27]
	Ba3(BO3)(CO3)F	549.84	trigonal	R3	a=10.1799 c=18.530 Z=9	1663.0	4.941		[28]
	Pb7O(OH)3(CO3)3(BO3)	1756.19	hexagonal	P63/mc	a=10.519 c=8.90 Z=2	853	6.839	SHG 4.5×KDP	[29]
Mereheadite	Pb47O24(OH)13Cl25(BO3)2(CO3)		monoclinic	Cm	a = 17.372, b = 27.942, c = 10.6661, β = 93.152o	5169.6			[30]
Britvinite	[Pb7(OH)3F(BO3)2(CO3)][Mg4.5(OH)3(Si5O14)]		triclinic	P1	a = 9.3409, b = 9.3579, c = 18.833 α = 80.365°, β = 75.816°, γ = 59.870° Z=2	1378.7	5.51	Biaxial (-) nα = 1.896 nβ = 1.903 nγ = 1.903 2V 20° Max birefringence δ = 0.007	[31]
Roymillerite	Pb24Mg9(Si10O28)(CO3)10(BO3)(SiO4)(OH)13O5		triclinic	P1	a = 9.316, b = 9.316, c = 26.463 α = 83.295°, β = 83.308°, γ = 60.023° Z=1	1971.2	5.973	Biaxial (-) nα = 1.860 nβ = 1.940 nγ = 1.940 2V 5° Max birefringence δ = 0.080	[32]