Alstonite Bindi L, Roberts A C, Biagioni C Mineralogical Magazine 84 (2020) 699-704 The crystal structure of alstonite, BaCa(CO3)2: an extraordinary example of 'hidden' complex twinning in large single crystals Locality: Fallowfield mine, Northumberland, England _database_code_amcsd 0020914 17.4360 17.4360 6.1295 90 90 120 P31m atom x y z Uiso U(1,1) U(2,2) U(3,3) U(1,2) U(1,3) U(2,3) Ba1 .65993 0 .09659 .01630 .00819 .0148 .0281 .00742 -.00027 .000 Ba2 .83960 0 .5958 .02955 .0323 .0186 .0332 .00928 -.0008 .000 Ba3 .50180 .15658 .09689 .01823 .01122 .0178 .02705 .00825 -.00011 .0003 Ca1 .16090 0 .0985 .0221 .0274 .0099 .0233 .0049 -.0007 .000 Ca2 .32472 0 .5971 .0271 .0295 .0175 .0302 .0088 .0008 .000 Ca3 .31951 .49915 .5962 .0269 .0308 .0165 .0333 .0117 .0008 -.0001 C1 .3328 .1624 .9278 .0271 .026 .036 .017 .014 -.0058 -.0040 C2 .3336 .1636 .4345 .0193 .024 .021 .015 .013 .0032 .0015 C3 0 0 .352 .018 .007 .007 .041 .0036 .000 .000 C4 0 0 .8388 .007 C5 .5015 0 .8287 .0168 C6 1/3 2/3 .4408 .028 .034 .034 .015 .017 .000 .000 C7 1/3 2/3 .919 .036 .044 .044 .019 .022 .000 .000 C8 .5022 0 .3576 .0170 .010 .004 .035 .0020 -.003 .000 O1 .4095 .2372 .9194 .0369 .027 .053 .031 .020 -.004 -.002 O2 .3294 .0839 .9268 .0312 .032 .016 .041 .009 .003 .0016 O3 .2547 .1619 .9425 .0373 .030 .037 .042 .015 -.001 -.006 O4 .3395 .2382 .4429 .0373 .017 .028 .059 .005 .001 -.001 O5 .2589 .0906 .4256 .0387 .029 .024 .053 .005 .002 .002 O6 .4081 .1597 .4494 .0340 .024 .032 .047 .015 .000 .005 O7 .0708 0 .8471 .0257 .023 .022 .031 .0110 -.001 .000 O8 .0742 .5780 .8367 .0355 .035 .014 .058 .012 .010 .011 O9 .4287 0 .8424 .0322 .018 .027 .055 .014 -.003 .000 O10 .6732 .2604 .9184 .0397 .036 .057 .035 .030 -.006 -.002 O11 .5981 .2565 .4545 .0480 .044 .059 .051 .033 .004 .003 O12 .5775 .0727 .3509 .0300 .031 .048 .0163 .024 -.0033 -.004 O13 .4311 0 .3504 .0348 .044 .044 .017 .022 .007 .000 O14 .0725 0 .350 .067 .033 .096 .092 .048 .001 .000