Chlorartinite, a volcanic exhalation product also found in industrial magnesia screed

The volcanic exhalation product chlorartinite, [Mg₂(CO₃)(H₂O)(OH)]Cl·H₂O, has recently been found to be a minor, and in some samples a major, component of magnesia floors for industrial use. In order to be able to perform quantitative phase analysis using the Rietveld method, its crystal structure was determined from high-resolution synchrotron powder diffraction data by the global optimization technique of simulated annealing and Rietveld refinement. The final R_p and R_wp values are 5.23% and 6.56%, respectively. Chlorartinite crystallizes in the rhombohedral space group R3c (No. 161), with a = 23.14422 (16) Å, c = 7.22333 (5) Å, V = 3350.84 (5) Å³, Z = 18. The building units of chlorartinite consist of MgO₆ octahedra forming 15-membered puckered rings which are interconnected by CO₃ triangular moieties. The rings are stacked to form a honeycomb-like three-dimensional framework structure with large isolated channels. Within the channels, free chlorine atoms and disordered water molecules are located.

Computing details

Figures

Magnesium chloride aqua carbonete hydrate

Crystal data

H5CO6Mg2Cl	Z = 18
Mr = 197.11	Dx = 1.758 Mg m^−3
Trigonal, R3c	Synchrotron radiation, λ = 0.64889 Å
a = 23.14422 (16) Å	T = 295 K
c = 7.22333 (5) Å	?, ? × ? × ? mm
V = 3350.84 (5) Å^3

Data collection

Refinement

Rp = 0.052	χ^2 = NOT FOUND
Rwp = 0.066	? data points
Rexp = 0.065
R(F^2) = 0.11080

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq	Occ. (<1)
Cl1	0.15058 (15)	0.19895 (14)	−0.1824 (9)	0.0308 (12)*
Mg1	0.2847 (2)	0.1193 (2)	−0.0737 (8)	0.0209 (15)*
Mg2	0.2800 (2)	0.3149 (2)	0.3367 (9)	0.0184 (15)*
O1	0.1859 (4)	0.0937 (4)	−0.0918 (14)	0.074 (3)*
O2	0.2959 (3)	0.1845 (3)	0.1532 (9)	0.0136 (15)*
O3	0.3207 (4)	0.2257 (3)	−0.1268 (7)	0.0136 (15)*
O4	0.3189 (4)	0.2873 (3)	0.1151 (8)	0.0136 (15)*
O5	0.2660 (4)	0.2374 (4)	0.5035 (11)	0.003 (3)*
O6	0.1885 (3)	0.2766 (3)	0.1732 (12)	0.029 (3)*
O7	0.0113 (18)	0.0704 (13)	−0.035 (4)	0.144 (12)*	0.4
O8	0.0078 (12)	0.0846 (9)	−0.246 (2)	0.141 (8)*	0.6
C1	0.3046 (2)	0.2308 (3)	0.0423 (7)	0.0136 (15)*

Geometric parameters (Å, º)

Mg1—O1	2.058 (8)	Mg2—O4	2.149 (7)
Mg1—O2	2.154 (7)	Mg2—O5	2.048 (8)
Mg1—O2	2.010 (6)	Mg2—O5	2.140 (8)
Mg1—O3	2.204 (7)	Mg2—O6	2.188 (9)
Mg1—O5	1.999 (8)	O2—C1	1.2700 (5)
Mg1—O6	2.280 (8)	O3—C1	1.2999 (5)
Mg2—O3	2.071 (8)	O4—C1	1.2900 (5)
Mg2—O4	2.087 (7)
O1—Mg1—O2	88.7 (3)	O4—Mg2—O6	86.6 (3)
O1—Mg1—O2	95.0 (4)	O4—Mg2—O5	84.8 (3)
O1—Mg1—O3	93.2 (4)	O4—Mg2—O5	89.6 (3)
O1—Mg1—O5	95.1 (4)	O4—Mg2—O6	168.3 (4)
O1—Mg1—O6	168.9 (4)	O5—Mg2—O5	174.4 (3)
O2—Mg1—O2	146.6 (3)	O5—Mg2—O6	105.4 (3)
O2—Mg1—O3	60.23 (15)	O5—Mg2—O6	80.2 (3)
O2—Mg1—O5	114.3 (3)	Mg1—O2—Mg1	129.4 (3)
O2—Mg1—O6	83.5 (3)	Mg1—O2—C1	91.4 (3)
O2—Mg1—O3	86.4 (3)	Mg1—O2—C1	138.9 (4)
O2—Mg1—O5	98.5 (4)	Mg1—O3—Mg2	144.6 (3)
O2—Mg1—O6	95.9 (4)	Mg1—O3—C1	88.4 (3)
O3—Mg1—O5	169.9 (4)	Mg2—O3—C1	126.3 (6)
O3—Mg1—O6	89.8 (3)	Mg2—O4—Mg2	92.3 (2)
O5—Mg1—O6	81.0 (3)	Mg2—O4—C1	133.8 (4)
O3—Mg2—O4	175.0 (4)	Mg2—O4—C1	131.4 (3)
O3—Mg2—O4	96.0 (3)	Mg1—O5—Mg2	124.1 (4)
O3—Mg2—O5	89.4 (3)	Mg1—O5—Mg2	101.0 (3)
O3—Mg2—O5	91.8 (3)	Mg2—O5—Mg2	93.7 (3)
O3—Mg2—O6	90.0 (3)	Mg1—O6—Mg2	91.4 (3)
O4—Mg2—O4	86.8 (2)	O2—C1—O3	116.65 (18)
O4—Mg2—O5	95.0 (3)	O2—C1—O4	116.76 (17)
O4—Mg2—O5	84.1 (3)	O3—C1—O4	122.33 (17)