Ca3SiO crystallizes in the orthorhombic Pnma space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a distorted linear geometry to four equivalent Si(1) and two equivalent O(1) atoms. In the second Ca site, Ca(2) is bonded in a distorted linear geometry to four equivalent Si(1) and two equivalent O(1) atoms. Si(1) is bonded to four equivalent Ca(2) and eight equivalent Ca(1) atoms to form distorted SiCa12 cuboctahedra that share corners with twelve equivalent Si(1)Ca12 cuboctahedra, faces with six equivalent Si(1)Ca12 cuboctahedra, and faces with eight equivalent O(1)Ca6 octahedra. O(1) is bonded to two equivalent Ca(2) and four equivalent Ca(1) atoms to form OCa6 octahedra that share corners with six equivalent O(1)Ca6 octahedra and faces with eight equivalent Si(1)Ca12 cuboctahedra. The corner-sharing octahedral tilt angles range from 8-11°.
Ca3SiO crystallizes in the orthorhombic Pnma space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a distorted linear geometry to four equivalent Si(1) and two equivalent O(1) atoms. There are a spread of Ca(1)-Si(1) bond distances ranging from 3.18-3.50 Å. Both Ca(1)-O(1) bond lengths are 2.36 Å. In the second Ca site, Ca(2) is bonded in a distorted linear geometry to four equivalent Si(1) and two equivalent O(1) atoms. There are a spread of Ca(2)-Si(1) bond distances ranging from 3.12-3.56 Å. Both Ca(2)-O(1) bond lengths are 2.36 Å. Si(1) is bonded to four equivalent Ca(2) and eight equivalent Ca(1) atoms to form distorted SiCa12 cuboctahedra that share corners with twelve equivalent Si(1)Ca12 cuboctahedra, faces with six equivalent Si(1)Ca12 cuboctahedra, and faces with eight equivalent O(1)Ca6 octahedra. O(1) is bonded to two equivalent Ca(2) and four equivalent Ca(1) atoms to form OCa6 octahedra that share corners with six equivalent O(1)Ca6 octahedra and faces with eight equivalent Si(1)Ca12 cuboctahedra. The corner-sharing octahedral tilt angles range from 8-11°.