The structure described by Ca3GeSi2O9 crystallizes in the triclinic P-1 space group. There are three inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to one O(1), one O(2), one O(3), one O(5), one O(7), and one O(9) atom to form distorted CaO6 octahedra that share  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra, corners with three equivalent Ge(1)O4 tetrahedra, edges with two equivalent Ca(2)O6 octahedra, and  an edgeedge with one Si(2)O4 tetrahedra. In the second Ca site, Ca(2) is bonded to one O(1), one O(3), one O(4), one O(5), one O(6), and one O(7) atom to form CaO6 octahedra that share  a cornercorner with one Ge(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra, corners with three equivalent Si(1)O4 tetrahedra, edges with two equivalent Ca(1)O6 octahedra, and  an edgeedge with one Si(2)O4 tetrahedra. In the third Ca site, Ca(3) is bonded in a 7-coordinate geometry to one O(1), one O(5), one O(8), two equivalent O(4), and two equivalent O(9) atoms. Ge(1) is bonded to one O(2), one O(7), one O(8), and one O(9) atom to form GeO4 tetrahedra that share  a cornercorner with one Ca(2)O6 octahedra, corners with three equivalent Ca(1)O6 octahedra,  a cornercorner with one Si(1)O4 tetrahedra, and  a cornercorner with one Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 48-63°. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(3), one O(4), one O(6), and one O(8) atom to form SiO4 tetrahedra that share  a cornercorner with one Ca(1)O6 octahedra, corners with three equivalent Ca(2)O6 octahedra,  a cornercorner with one Ge(1)O4 tetrahedra, and  a cornercorner with one Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 44-60°. In the second Si site, Si(2) is bonded to one O(1), one O(2), one O(5), and one O(6) atom to form SiO4 tetrahedra that share  a cornercorner with one Ca(1)O6 octahedra,  a cornercorner with one Ca(2)O6 octahedra,  a cornercorner with one Ge(1)O4 tetrahedra,  a cornercorner with one Si(1)O4 tetrahedra,  an edgeedge with one Ca(1)O6 octahedra, and  an edgeedge with one Ca(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 53-54°. There are nine inequivalent O sites. In the first O site, O(1) is bonded in a distorted rectangular see-saw-like geometry to one Ca(1), one Ca(2), one Ca(3), and one Si(2) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Ca(1), one Ge(1), and one Si(2) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Ca(1), one Ca(2), and one Si(1) atom. In the fourth O site, O(4) is bonded to one Ca(2), two equivalent Ca(3), and one Si(1) atom to form distorted OCa3Si trigonal pyramids that share corners with four equivalent O(9)Ca3Ge tetrahedra and  an edgeedge with one O(4)Ca3Si trigonal pyramid. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to one Ca(1), one Ca(2), one Ca(3), and one Si(2) atom. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to one Ca(2), one Si(1), and one Si(2) atom. In the seventh O site, O(7) is bonded in a trigonal planar geometry to one Ca(1), one Ca(2), and one Ge(1) atom. In the eighth O site, O(8) is bonded in a distorted bent 150 degrees geometry to one Ca(3), one Ge(1), and one Si(1) atom. In the ninth O site, O(9) is bonded to one Ca(1), two equivalent Ca(3), and one Ge(1) atom to form distorted OCa3Ge tetrahedra that share corners with four equivalent O(4)Ca3Si trigonal pyramids and  an edgeedge with one O(9)Ca3Ge tetrahedra. is represented by the CIF card [CIF]
data_Ca3Si2GeO9
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.203
_cell_length_b   7.492
_cell_length_c   8.093
_cell_angle_alpha   103.215
_cell_angle_beta   95.439
_cell_angle_gamma   90.678
_symmetry_Int_Tables_number   1
_cell_volume   422.957
_cell_formula_units_Z   2
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
  Ca  Ca0  1  0.762  0.420  0.201  1.0
  Ca  Ca1  1  0.238  0.580  0.799  1.0
  Ca  Ca2  1  0.763  0.931  0.207  1.0
  Ca  Ca3  1  0.237  0.069  0.793  1.0
  Ca  Ca4  1  0.471  0.246  0.496  1.0
  Ca  Ca5  1  0.529  0.754  0.504  1.0
  Si  Si6  1  0.269  0.953  0.186  1.0
  Si  Si7  1  0.731  0.047  0.814  1.0
  Si  Si8  1  0.054  0.725  0.398  1.0
  Si  Si9  1  0.946  0.275  0.602  1.0
  Ge  Ge10  1  0.271  0.390  0.184  1.0
  Ge  Ge11  1  0.729  0.610  0.816  1.0
  O  O12  1  0.800  0.231  0.431  1.0
  O  O13  1  0.200  0.769  0.569  1.0
  O  O14  1  0.080  0.515  0.276  1.0
  O  O15  1  0.920  0.485  0.724  1.0
  O  O16  1  0.738  0.130  0.019  1.0
  O  O17  1  0.262  0.870  0.981  1.0
  O  O18  1  0.465  0.936  0.300  1.0
  O  O19  1  0.535  0.064  0.700  1.0
  O  O20  1  0.828  0.729  0.401  1.0
  O  O21  1  0.172  0.271  0.599  1.0
  O  O22  1  0.094  0.867  0.269  1.0
  O  O23  1  0.906  0.133  0.731  1.0
  O  O24  1  0.731  0.632  0.033  1.0
  O  O25  1  0.269  0.368  0.967  1.0
  O  O26  1  0.221  0.173  0.229  1.0
  O  O27  1  0.779  0.827  0.771  1.0
  O  O28  1  0.478  0.466  0.313  1.0
  O  O29  1  0.522  0.534  0.687  1.0
[/CIF]
.
The structure described by Ca3GeSi2O9 crystallizes in the triclinic P-1 space group. There are three inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to one O(1), one O(2), one O(3), one O(5), one O(7), and one O(9) atom to form distorted CaO6 octahedra that share  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra, corners with three equivalent Ge(1)O4 tetrahedra, edges with two equivalent Ca(2)O6 octahedra, and  an edgeedge with one Si(2)O4 tetrahedra. In the second Ca site, Ca(2) is bonded to one O(1), one O(3), one O(4), one O(5), one O(6), and one O(7) atom to form CaO6 octahedra that share  a cornercorner with one Ge(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra, corners with three equivalent Si(1)O4 tetrahedra, edges with two equivalent Ca(1)O6 octahedra, and  an edgeedge with one Si(2)O4 tetrahedra. In the third Ca site, Ca(3) is bonded in a 7-coordinate geometry to one O(1), one O(5), one O(8), two equivalent O(4), and two equivalent O(9) atoms. Ge(1) is bonded to one O(2), one O(7), one O(8), and one O(9) atom to form GeO4 tetrahedra that share  a cornercorner with one Ca(2)O6 octahedra, corners with three equivalent Ca(1)O6 octahedra,  a cornercorner with one Si(1)O4 tetrahedra, and  a cornercorner with one Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 48-63°. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(3), one O(4), one O(6), and one O(8) atom to form SiO4 tetrahedra that share  a cornercorner with one Ca(1)O6 octahedra, corners with three equivalent Ca(2)O6 octahedra,  a cornercorner with one Ge(1)O4 tetrahedra, and  a cornercorner with one Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 44-60°. In the second Si site, Si(2) is bonded to one O(1), one O(2), one O(5), and one O(6) atom to form SiO4 tetrahedra that share  a cornercorner with one Ca(1)O6 octahedra,  a cornercorner with one Ca(2)O6 octahedra,  a cornercorner with one Ge(1)O4 tetrahedra,  a cornercorner with one Si(1)O4 tetrahedra,  an edgeedge with one Ca(1)O6 octahedra, and  an edgeedge with one Ca(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 53-54°. There are nine inequivalent O sites. In the first O site, O(1) is bonded in a distorted rectangular see-saw-like geometry to one Ca(1), one Ca(2), one Ca(3), and one Si(2) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Ca(1), one Ge(1), and one Si(2) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Ca(1), one Ca(2), and one Si(1) atom. In the fourth O site, O(4) is bonded to one Ca(2), two equivalent Ca(3), and one Si(1) atom to form distorted OCa3Si trigonal pyramids that share corners with four equivalent O(9)Ca3Ge tetrahedra and  an edgeedge with one O(4)Ca3Si trigonal pyramid. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to one Ca(1), one Ca(2), one Ca(3), and one Si(2) atom. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to one Ca(2), one Si(1), and one Si(2) atom. In the seventh O site, O(7) is bonded in a trigonal planar geometry to one Ca(1), one Ca(2), and one Ge(1) atom. In the eighth O site, O(8) is bonded in a distorted bent 150 degrees geometry to one Ca(3), one Ge(1), and one Si(1) atom. In the ninth O site, O(9) is bonded to one Ca(1), two equivalent Ca(3), and one Ge(1) atom to form distorted OCa3Ge tetrahedra that share corners with four equivalent O(4)Ca3Si trigonal pyramids and  an edgeedge with one O(9)Ca3Ge tetrahedra. is represented by the CIF card [CIF]
data_Ca3Si2GeO9
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.203
_cell_length_b   7.492
_cell_length_c   8.093
_cell_angle_alpha   103.215
_cell_angle_beta   95.439
_cell_angle_gamma   90.678
_symmetry_Int_Tables_number   1
_cell_volume   422.957
_cell_formula_units_Z   2
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
  Ca  Ca0  1  0.762  0.420  0.201  1.0
  Ca  Ca1  1  0.238  0.580  0.799  1.0
  Ca  Ca2  1  0.763  0.931  0.207  1.0
  Ca  Ca3  1  0.237  0.069  0.793  1.0
  Ca  Ca4  1  0.471  0.246  0.496  1.0
  Ca  Ca5  1  0.529  0.754  0.504  1.0
  Si  Si6  1  0.269  0.953  0.186  1.0
  Si  Si7  1  0.731  0.047  0.814  1.0
  Si  Si8  1  0.054  0.725  0.398  1.0
  Si  Si9  1  0.946  0.275  0.602  1.0
  Ge  Ge10  1  0.271  0.390  0.184  1.0
  Ge  Ge11  1  0.729  0.610  0.816  1.0
  O  O12  1  0.800  0.231  0.431  1.0
  O  O13  1  0.200  0.769  0.569  1.0
  O  O14  1  0.080  0.515  0.276  1.0
  O  O15  1  0.920  0.485  0.724  1.0
  O  O16  1  0.738  0.130  0.019  1.0
  O  O17  1  0.262  0.870  0.981  1.0
  O  O18  1  0.465  0.936  0.300  1.0
  O  O19  1  0.535  0.064  0.700  1.0
  O  O20  1  0.828  0.729  0.401  1.0
  O  O21  1  0.172  0.271  0.599  1.0
  O  O22  1  0.094  0.867  0.269  1.0
  O  O23  1  0.906  0.133  0.731  1.0
  O  O24  1  0.731  0.632  0.033  1.0
  O  O25  1  0.269  0.368  0.967  1.0
  O  O26  1  0.221  0.173  0.229  1.0
  O  O27  1  0.779  0.827  0.771  1.0
  O  O28  1  0.478  0.466  0.313  1.0
  O  O29  1  0.522  0.534  0.687  1.0
[/CIF]
.