Tweddillite Armbruster T, Gnos E, Dixon R, Gutzmer J, Hejny C, Dobelin N, Medenbach O Mineralogical Magazine 66 (2002) 137-150 Manganvesuvianite and tweddillite, two new Mn3+-silicate minerals from the Kalahari manganese fields, South Africa Locality: Kalahari manganese fields, South Africa _database_code_amcsd 0014561 8.934 5.718 10.325 90 114.54 90 P2_1/m atom x y z occ Biso CaA1 .7646 .75 .1575 .92 SrA2 .5941 .75 .42163 1.03 AlM1 0 0 0 .43 .64 Mn3+M1 0 0 0 .48 .64 Fe3+M1 0 0 0 .09 .64 AlM2 0 0 .5 .66 Mn3+M3 .2954 .25 .2181 5/6 .90 Fe3+M3 .2954 .25 .2181 1/6 .90 Si1 .3417 .75 .0411 .95 Si2 .6877 .25 .2787 .85 Si3 .1803 .75 .3150 .86 O1 .2389 .9915 .0386 1.42 O2 .2984 .9786 .3480 1.14 O3 .7967 .0160 .3433 1.17 O4 .0600 .25 .1312 .9 O5 .0369 .75 .1479 1.0 O6 .0661 .75 .4061 1.0 O7 .5174 .75 .1691 1.4 O8 .5277 .25 .3110 1.0 O9 .6323 .25 .1063 1.8 O10 .0815 .25 .4293 .9 H10 .06 .25 .339 3.95