The structure described by K2CaMg5Si8(HO12)2 is Esseneite-derived structured and crystallizes in the triclinic P1 space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a 11-coordinate geometry to one H(2), one O(1), one O(10), one O(15), one O(16), one O(17), one O(18), one O(2), one O(7), one O(8), and one O(9) atom. In the second K site, K(2) is bonded in a 8-coordinate geometry to one O(11), one O(14), one O(16), one O(17), one O(22), one O(23), one O(8), and one O(9) atom. Ca(1) is bonded in a 8-coordinate geometry to one O(10), one O(12), one O(13), one O(15), one O(18), one O(21), one O(24), and one O(7) atom. There are five inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to one O(11), one O(14), one O(19), one O(20), one O(3), and one O(6) atom to form MgO6 octahedra that share  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra,  a cornercorner with one Si(5)O4 tetrahedra,  a cornercorner with one Si(8)O4 tetrahedra,  an edgeedge with one Mg(2)O6 octahedra, edges with two equivalent Mg(3)O6 octahedra, and edges with two equivalent Mg(5)O6 octahedra. In the second Mg site, Mg(2) is bonded to one O(12), one O(13), one O(19), one O(20), one O(4), and one O(5) atom to form MgO6 octahedra that share  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra,  a cornercorner with one Si(6)O4 tetrahedra,  a cornercorner with one Si(7)O4 tetrahedra,  an edgeedge with one Mg(1)O6 octahedra, edges with two equivalent Mg(4)O6 octahedra, and edges with two equivalent Mg(5)O6 octahedra. In the third Mg site, Mg(3) is bonded to one O(11), one O(14), one O(22), one O(23), one O(3), and one O(6) atom to form distorted MgO6 octahedra that share  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra,  a cornercorner with one Si(5)O4 tetrahedra,  a cornercorner with one Si(8)O4 tetrahedra,  an edgeedge with one Mg(5)O6 octahedra, and edges with two equivalent Mg(1)O6 octahedra. In the fourth Mg site, Mg(4) is bonded to one O(12), one O(13), one O(21), one O(24), one O(4), and one O(5) atom to form MgO6 octahedra that share  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra,  a cornercorner with one Si(6)O4 tetrahedra,  a cornercorner with one Si(7)O4 tetrahedra,  an edgeedge with one Mg(5)O6 octahedra, and edges with two equivalent Mg(2)O6 octahedra. In the fifth Mg site, Mg(5) is bonded to one O(19), one O(20), one O(3), one O(4), one O(5), and one O(6) atom to form MgO6 octahedra that share  a cornercorner with one Si(5)O4 tetrahedra,  a cornercorner with one Si(6)O4 tetrahedra,  a cornercorner with one Si(7)O4 tetrahedra,  a cornercorner with one Si(8)O4 tetrahedra,  an edgeedge with one Mg(3)O6 octahedra,  an edgeedge with one Mg(4)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, and edges with two equivalent Mg(2)O6 octahedra. There are eight inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(11), one O(15), one O(21), and one O(7) atom to form SiO4 tetrahedra that share  a cornercorner with one Mg(1)O6 octahedra,  a cornercorner with one Mg(3)O6 octahedra,  a cornercorner with one Mg(4)O6 octahedra, and corners with two equivalent Si(5)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 33-55°. In the second Si site, Si(2) is bonded to one O(12), one O(16), one O(22), and one O(8) atom to form SiO4 tetrahedra that share  a cornercorner with one Mg(2)O6 octahedra,  a cornercorner with one Mg(3)O6 octahedra,  a cornercorner with one Mg(4)O6 octahedra, and corners with two equivalent Si(6)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 30-58°. In the third Si site, Si(3) is bonded to one O(13), one O(17), one O(23), and one O(9) atom to form SiO4 tetrahedra that share  a cornercorner with one Mg(2)O6 octahedra,  a cornercorner with one Mg(3)O6 octahedra,  a cornercorner with one Mg(4)O6 octahedra, and corners with two equivalent Si(7)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 30-58°. In the fourth Si site, Si(4) is bonded to one O(10), one O(14), one O(18), and one O(24) atom to form SiO4 tetrahedra that share  a cornercorner with one Mg(1)O6 octahedra,  a cornercorner with one Mg(3)O6 octahedra,  a cornercorner with one Mg(4)O6 octahedra, and corners with two equivalent Si(8)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 33-55°. In the fifth Si site, Si(5) is bonded to one O(1), one O(15), one O(3), and one O(7) atom to form SiO4 tetrahedra that share  a cornercorner with one Mg(1)O6 octahedra,  a cornercorner with one Mg(3)O6 octahedra,  a cornercorner with one Mg(5)O6 octahedra,  a cornercorner with one Si(6)O4 tetrahedra, and corners with two equivalent Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 59-60°. In the sixth Si site, Si(6) is bonded to one O(1), one O(16), one O(4), and one O(8) atom to form SiO4 tetrahedra that share  a cornercorner with one Mg(2)O6 octahedra,  a cornercorner with one Mg(4)O6 octahedra,  a cornercorner with one Mg(5)O6 octahedra,  a cornercorner with one Si(5)O4 tetrahedra, and corners with two equivalent Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 59-61°. In the seventh Si site, Si(7) is bonded to one O(17), one O(2), one O(5), and one O(9) atom to form SiO4 tetrahedra that share  a cornercorner with one Mg(2)O6 octahedra,  a cornercorner with one Mg(4)O6 octahedra,  a cornercorner with one Mg(5)O6 octahedra,  a cornercorner with one Si(8)O4 tetrahedra, and corners with two equivalent Si(3)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 59-61°. In the eighth Si site, Si(8) is bonded to one O(10), one O(18), one O(2), and one O(6) atom to form SiO4 tetrahedra that share  a cornercorner with one Mg(1)O6 octahedra,  a cornercorner with one Mg(3)O6 octahedra,  a cornercorner with one Mg(5)O6 octahedra,  a cornercorner with one Si(7)O4 tetrahedra, and corners with two equivalent Si(4)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 59-60°. There are two inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one O(19) atom. In the second H site, H(2) is bonded in a single-bond geometry to one K(1) and one O(20) atom. There are twenty-four inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one K(1), one Si(5), and one Si(6) atom. In the second O site, O(2) is bonded in a 2-coordinate geometry to one K(1), one Si(7), and one Si(8) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Mg(1), one Mg(3), one Mg(5), and one Si(5) atom. In the fourth O site, O(4) is bonded to one Mg(2), one Mg(4), one Mg(5), and one Si(6) atom to form a mixture of distorted edge and corner-sharing OMg3Si tetrahedra. In the fifth O site, O(5) is bonded to one Mg(2), one Mg(4), one Mg(5), and one Si(7) atom to form a mixture of distorted edge and corner-sharing OMg3Si trigonal pyramids. In the sixth O site, O(6) is bonded to one Mg(1), one Mg(3), one Mg(5), and one Si(8) atom to form distorted corner-sharing OMg3Si trigonal pyramids. In the seventh O site, O(7) is bonded in a 2-coordinate geometry to one K(1), one Ca(1), one Si(1), and one Si(5) atom. In the eighth O site, O(8) is bonded in a 2-coordinate geometry to one K(1), one K(2), one Si(2), and one Si(6) atom. In the ninth O site, O(9) is bonded in a 2-coordinate geometry to one K(1), one K(2), one Si(3), and one Si(7) atom. In the tenth O site, O(10) is bonded in a 2-coordinate geometry to one K(1), one Ca(1), one Si(4), and one Si(8) atom. In the eleventh O site, O(11) is bonded in a 4-coordinate geometry to one K(2), one Mg(1), one Mg(3), and one Si(1) atom. In the twelfth O site, O(12) is bonded in a distorted rectangular see-saw-like geometry to one Ca(1), one Mg(2), one Mg(4), and one Si(2) atom. In the thirteenth O site, O(13) is bonded in a distorted rectangular see-saw-like geometry to one Ca(1), one Mg(2), one Mg(4), and one Si(3) atom. In the fourteenth O site, O(14) is bonded in a 4-coordinate geometry to one K(2), one Mg(1), one Mg(3), and one Si(4) atom. In the fifteenth O site, O(15) is bonded in a 2-coordinate geometry to one K(1), one Ca(1), one Si(1), and one Si(5) atom. In the sixteenth O site, O(16) is bonded in a 2-coordinate geometry to one K(1), one K(2), one Si(2), and one Si(6) atom. In the seventeenth O site, O(17) is bonded in a 2-coordinate geometry to one K(1), one K(2), one Si(3), and one Si(7) atom. In the eighteenth O site, O(18) is bonded in a 2-coordinate geometry to one K(1), one Ca(1), one Si(4), and one Si(8) atom. In the nineteenth O site, O(19) is bonded in a distorted single-bond geometry to one Mg(1), one Mg(2), one Mg(5), and one H(1) atom. In the twentieth O site, O(20) is bonded in a distorted single-bond geometry to one Mg(1), one Mg(2), one Mg(5), and one H(2) atom. In the twenty-first O site, O(21) is bonded in a distorted T-shaped geometry to one Ca(1), one Mg(4), and one Si(1) atom. In the twenty-second O site, O(22) is bonded in a distorted T-shaped geometry to one K(2), one Mg(3), and one Si(2) atom. In the twenty-third O site, O(23) is bonded in a distorted T-shaped geometry to one K(2), one Mg(3), and one Si(3) atom. In the twenty-fourth O site, O(24) is bonded in a distorted T-shaped geometry to one Ca(1), one Mg(4), and one Si(4) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_K2CaMg5Si8(HO12)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.339
_cell_length_b   10.308
_cell_length_c   10.513
_cell_angle_alpha   115.145
_cell_angle_beta   97.362
_cell_angle_gamma   104.870
_symmetry_Int_Tables_number   1
_cell_volume   487.283
_cell_formula_units_Z   1
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
loop_
 _atom_site_type_symbol
 _atom_site_label
 _atom_site_symmetry_multiplicity
 _atom_site_fract_x
 _atom_site_fract_y
 _atom_site_fract_z
 _atom_site_occupancy
  K  K0  1  0.487  0.510  0.003  1.0
  K  K1  1  0.215  0.715  0.430  1.0
  Ca  Ca2  1  0.778  0.278  0.556  1.0
  Mg  Mg3  1  0.411  0.911  0.821  1.0
  Mg  Mg4  1  0.588  0.089  0.177  1.0
  Mg  Mg5  1  0.818  0.818  0.636  1.0
  Mg  Mg6  1  0.179  0.179  0.357  1.0
  Mg  Mg7  1  1.000  1.000  0.998  1.0
  Si  Si8  1  0.300  0.113  0.659  1.0
  Si  Si9  1  0.637  0.449  0.342  1.0
  Si  Si10  1  0.705  0.893  0.342  1.0
  Si  Si11  1  0.359  0.546  0.659  1.0
  Si  Si12  1  0.881  0.185  0.829  1.0
  Si  Si13  1  0.046  0.352  0.168  1.0
  Si  Si14  1  0.121  0.816  0.168  1.0
  Si  Si15  1  0.949  0.644  0.829  1.0
  H  H16  1  0.446  0.201  0.001  1.0
  H  H17  1  0.554  0.801  0.001  1.0
  O  O18  1  0.021  0.325  0.999  1.0
  O  O19  1  0.979  0.673  0.999  1.0
  O  O20  1  0.801  0.022  0.826  1.0
  O  O21  1  0.975  0.193  0.174  1.0
  O  O22  1  0.200  0.981  0.174  1.0
  O  O23  1  0.025  0.804  0.827  1.0
  O  O24  1  0.104  0.213  0.739  1.0
  O  O25  1  0.363  0.461  0.254  1.0
  O  O26  1  0.891  0.793  0.254  1.0
  O  O27  1  0.635  0.526  0.739  1.0
  O  O28  1  0.220  0.956  0.669  1.0
  O  O29  1  0.562  0.287  0.346  1.0
  O  O30  1  0.784  0.060  0.346  1.0
  O  O31  1  0.448  0.713  0.669  1.0
  O  O32  1  0.622  0.223  0.769  1.0
  O  O33  1  0.836  0.441  0.226  1.0
  O  O34  1  0.391  0.785  0.226  1.0
  O  O35  1  0.148  0.547  0.769  1.0
  O  O36  1  0.389  0.104  0.002  1.0
  O  O37  1  0.614  0.899  0.002  1.0
  O  O38  1  0.324  0.123  0.512  1.0
  O  O39  1  0.781  0.600  0.495  1.0
  O  O40  1  0.713  0.895  0.495  1.0
  O  O41  1  0.187  0.389  0.512  1.0
[/CIF]
.
The structure described by K2CaMg5Si8(HO12)2 is Esseneite-derived structured and crystallizes in the triclinic P1 space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a 11-coordinate geometry to one H(2), one O(1), one O(10), one O(15), one O(16), one O(17), one O(18), one O(2), one O(7), one O(8), and one O(9) atom. In the second K site, K(2) is bonded in a 8-coordinate geometry to one O(11), one O(14), one O(16), one O(17), one O(22), one O(23), one O(8), and one O(9) atom. Ca(1) is bonded in a 8-coordinate geometry to one O(10), one O(12), one O(13), one O(15), one O(18), one O(21), one O(24), and one O(7) atom. There are five inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to one O(11), one O(14), one O(19), one O(20), one O(3), and one O(6) atom to form MgO6 octahedra that share  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra,  a cornercorner with one Si(5)O4 tetrahedra,  a cornercorner with one Si(8)O4 tetrahedra,  an edgeedge with one Mg(2)O6 octahedra, edges with two equivalent Mg(3)O6 octahedra, and edges with two equivalent Mg(5)O6 octahedra. In the second Mg site, Mg(2) is bonded to one O(12), one O(13), one O(19), one O(20), one O(4), and one O(5) atom to form MgO6 octahedra that share  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra,  a cornercorner with one Si(6)O4 tetrahedra,  a cornercorner with one Si(7)O4 tetrahedra,  an edgeedge with one Mg(1)O6 octahedra, edges with two equivalent Mg(4)O6 octahedra, and edges with two equivalent Mg(5)O6 octahedra. In the third Mg site, Mg(3) is bonded to one O(11), one O(14), one O(22), one O(23), one O(3), and one O(6) atom to form distorted MgO6 octahedra that share  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra,  a cornercorner with one Si(5)O4 tetrahedra,  a cornercorner with one Si(8)O4 tetrahedra,  an edgeedge with one Mg(5)O6 octahedra, and edges with two equivalent Mg(1)O6 octahedra. In the fourth Mg site, Mg(4) is bonded to one O(12), one O(13), one O(21), one O(24), one O(4), and one O(5) atom to form MgO6 octahedra that share  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra,  a cornercorner with one Si(6)O4 tetrahedra,  a cornercorner with one Si(7)O4 tetrahedra,  an edgeedge with one Mg(5)O6 octahedra, and edges with two equivalent Mg(2)O6 octahedra. In the fifth Mg site, Mg(5) is bonded to one O(19), one O(20), one O(3), one O(4), one O(5), and one O(6) atom to form MgO6 octahedra that share  a cornercorner with one Si(5)O4 tetrahedra,  a cornercorner with one Si(6)O4 tetrahedra,  a cornercorner with one Si(7)O4 tetrahedra,  a cornercorner with one Si(8)O4 tetrahedra,  an edgeedge with one Mg(3)O6 octahedra,  an edgeedge with one Mg(4)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, and edges with two equivalent Mg(2)O6 octahedra. There are eight inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(11), one O(15), one O(21), and one O(7) atom to form SiO4 tetrahedra that share  a cornercorner with one Mg(1)O6 octahedra,  a cornercorner with one Mg(3)O6 octahedra,  a cornercorner with one Mg(4)O6 octahedra, and corners with two equivalent Si(5)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 33-55°. In the second Si site, Si(2) is bonded to one O(12), one O(16), one O(22), and one O(8) atom to form SiO4 tetrahedra that share  a cornercorner with one Mg(2)O6 octahedra,  a cornercorner with one Mg(3)O6 octahedra,  a cornercorner with one Mg(4)O6 octahedra, and corners with two equivalent Si(6)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 30-58°. In the third Si site, Si(3) is bonded to one O(13), one O(17), one O(23), and one O(9) atom to form SiO4 tetrahedra that share  a cornercorner with one Mg(2)O6 octahedra,  a cornercorner with one Mg(3)O6 octahedra,  a cornercorner with one Mg(4)O6 octahedra, and corners with two equivalent Si(7)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 30-58°. In the fourth Si site, Si(4) is bonded to one O(10), one O(14), one O(18), and one O(24) atom to form SiO4 tetrahedra that share  a cornercorner with one Mg(1)O6 octahedra,  a cornercorner with one Mg(3)O6 octahedra,  a cornercorner with one Mg(4)O6 octahedra, and corners with two equivalent Si(8)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 33-55°. In the fifth Si site, Si(5) is bonded to one O(1), one O(15), one O(3), and one O(7) atom to form SiO4 tetrahedra that share  a cornercorner with one Mg(1)O6 octahedra,  a cornercorner with one Mg(3)O6 octahedra,  a cornercorner with one Mg(5)O6 octahedra,  a cornercorner with one Si(6)O4 tetrahedra, and corners with two equivalent Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 59-60°. In the sixth Si site, Si(6) is bonded to one O(1), one O(16), one O(4), and one O(8) atom to form SiO4 tetrahedra that share  a cornercorner with one Mg(2)O6 octahedra,  a cornercorner with one Mg(4)O6 octahedra,  a cornercorner with one Mg(5)O6 octahedra,  a cornercorner with one Si(5)O4 tetrahedra, and corners with two equivalent Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 59-61°. In the seventh Si site, Si(7) is bonded to one O(17), one O(2), one O(5), and one O(9) atom to form SiO4 tetrahedra that share  a cornercorner with one Mg(2)O6 octahedra,  a cornercorner with one Mg(4)O6 octahedra,  a cornercorner with one Mg(5)O6 octahedra,  a cornercorner with one Si(8)O4 tetrahedra, and corners with two equivalent Si(3)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 59-61°. In the eighth Si site, Si(8) is bonded to one O(10), one O(18), one O(2), and one O(6) atom to form SiO4 tetrahedra that share  a cornercorner with one Mg(1)O6 octahedra,  a cornercorner with one Mg(3)O6 octahedra,  a cornercorner with one Mg(5)O6 octahedra,  a cornercorner with one Si(7)O4 tetrahedra, and corners with two equivalent Si(4)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 59-60°. There are two inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one O(19) atom. In the second H site, H(2) is bonded in a single-bond geometry to one K(1) and one O(20) atom. There are twenty-four inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one K(1), one Si(5), and one Si(6) atom. In the second O site, O(2) is bonded in a 2-coordinate geometry to one K(1), one Si(7), and one Si(8) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Mg(1), one Mg(3), one Mg(5), and one Si(5) atom. In the fourth O site, O(4) is bonded to one Mg(2), one Mg(4), one Mg(5), and one Si(6) atom to form a mixture of distorted edge and corner-sharing OMg3Si tetrahedra. In the fifth O site, O(5) is bonded to one Mg(2), one Mg(4), one Mg(5), and one Si(7) atom to form a mixture of distorted edge and corner-sharing OMg3Si trigonal pyramids. In the sixth O site, O(6) is bonded to one Mg(1), one Mg(3), one Mg(5), and one Si(8) atom to form distorted corner-sharing OMg3Si trigonal pyramids. In the seventh O site, O(7) is bonded in a 2-coordinate geometry to one K(1), one Ca(1), one Si(1), and one Si(5) atom. In the eighth O site, O(8) is bonded in a 2-coordinate geometry to one K(1), one K(2), one Si(2), and one Si(6) atom. In the ninth O site, O(9) is bonded in a 2-coordinate geometry to one K(1), one K(2), one Si(3), and one Si(7) atom. In the tenth O site, O(10) is bonded in a 2-coordinate geometry to one K(1), one Ca(1), one Si(4), and one Si(8) atom. In the eleventh O site, O(11) is bonded in a 4-coordinate geometry to one K(2), one Mg(1), one Mg(3), and one Si(1) atom. In the twelfth O site, O(12) is bonded in a distorted rectangular see-saw-like geometry to one Ca(1), one Mg(2), one Mg(4), and one Si(2) atom. In the thirteenth O site, O(13) is bonded in a distorted rectangular see-saw-like geometry to one Ca(1), one Mg(2), one Mg(4), and one Si(3) atom. In the fourteenth O site, O(14) is bonded in a 4-coordinate geometry to one K(2), one Mg(1), one Mg(3), and one Si(4) atom. In the fifteenth O site, O(15) is bonded in a 2-coordinate geometry to one K(1), one Ca(1), one Si(1), and one Si(5) atom. In the sixteenth O site, O(16) is bonded in a 2-coordinate geometry to one K(1), one K(2), one Si(2), and one Si(6) atom. In the seventeenth O site, O(17) is bonded in a 2-coordinate geometry to one K(1), one K(2), one Si(3), and one Si(7) atom. In the eighteenth O site, O(18) is bonded in a 2-coordinate geometry to one K(1), one Ca(1), one Si(4), and one Si(8) atom. In the nineteenth O site, O(19) is bonded in a distorted single-bond geometry to one Mg(1), one Mg(2), one Mg(5), and one H(1) atom. In the twentieth O site, O(20) is bonded in a distorted single-bond geometry to one Mg(1), one Mg(2), one Mg(5), and one H(2) atom. In the twenty-first O site, O(21) is bonded in a distorted T-shaped geometry to one Ca(1), one Mg(4), and one Si(1) atom. In the twenty-second O site, O(22) is bonded in a distorted T-shaped geometry to one K(2), one Mg(3), and one Si(2) atom. In the twenty-third O site, O(23) is bonded in a distorted T-shaped geometry to one K(2), one Mg(3), and one Si(3) atom. In the twenty-fourth O site, O(24) is bonded in a distorted T-shaped geometry to one Ca(1), one Mg(4), and one Si(4) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_K2CaMg5Si8(HO12)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.339
_cell_length_b   10.308
_cell_length_c   10.513
_cell_angle_alpha   115.145
_cell_angle_beta   97.362
_cell_angle_gamma   104.870
_symmetry_Int_Tables_number   1
_cell_volume   487.283
_cell_formula_units_Z   1
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
loop_
 _atom_site_type_symbol
 _atom_site_label
 _atom_site_symmetry_multiplicity
 _atom_site_fract_x
 _atom_site_fract_y
 _atom_site_fract_z
 _atom_site_occupancy
  K  K0  1  0.487  0.510  0.003  1.0
  K  K1  1  0.215  0.715  0.430  1.0
  Ca  Ca2  1  0.778  0.278  0.556  1.0
  Mg  Mg3  1  0.411  0.911  0.821  1.0
  Mg  Mg4  1  0.588  0.089  0.177  1.0
  Mg  Mg5  1  0.818  0.818  0.636  1.0
  Mg  Mg6  1  0.179  0.179  0.357  1.0
  Mg  Mg7  1  1.000  1.000  0.998  1.0
  Si  Si8  1  0.300  0.113  0.659  1.0
  Si  Si9  1  0.637  0.449  0.342  1.0
  Si  Si10  1  0.705  0.893  0.342  1.0
  Si  Si11  1  0.359  0.546  0.659  1.0
  Si  Si12  1  0.881  0.185  0.829  1.0
  Si  Si13  1  0.046  0.352  0.168  1.0
  Si  Si14  1  0.121  0.816  0.168  1.0
  Si  Si15  1  0.949  0.644  0.829  1.0
  H  H16  1  0.446  0.201  0.001  1.0
  H  H17  1  0.554  0.801  0.001  1.0
  O  O18  1  0.021  0.325  0.999  1.0
  O  O19  1  0.979  0.673  0.999  1.0
  O  O20  1  0.801  0.022  0.826  1.0
  O  O21  1  0.975  0.193  0.174  1.0
  O  O22  1  0.200  0.981  0.174  1.0
  O  O23  1  0.025  0.804  0.827  1.0
  O  O24  1  0.104  0.213  0.739  1.0
  O  O25  1  0.363  0.461  0.254  1.0
  O  O26  1  0.891  0.793  0.254  1.0
  O  O27  1  0.635  0.526  0.739  1.0
  O  O28  1  0.220  0.956  0.669  1.0
  O  O29  1  0.562  0.287  0.346  1.0
  O  O30  1  0.784  0.060  0.346  1.0
  O  O31  1  0.448  0.713  0.669  1.0
  O  O32  1  0.622  0.223  0.769  1.0
  O  O33  1  0.836  0.441  0.226  1.0
  O  O34  1  0.391  0.785  0.226  1.0
  O  O35  1  0.148  0.547  0.769  1.0
  O  O36  1  0.389  0.104  0.002  1.0
  O  O37  1  0.614  0.899  0.002  1.0
  O  O38  1  0.324  0.123  0.512  1.0
  O  O39  1  0.781  0.600  0.495  1.0
  O  O40  1  0.713  0.895  0.495  1.0
  O  O41  1  0.187  0.389  0.512  1.0
[/CIF]
.