view crystal in whole frame

Atomic Positional Parameters
C 8a 0.0000 0.0000 0.0000

Reference
DP Riley (1944) Nature, 153, 587

Mineral Chemistry
The structure of diamond, one of the first crystal structures to be determined by X-ray diffraction, consists of carbon atoms linked to four other carbons in a tetrahedral arrangement. These four equivalent covalent bonds arise from hybridisation of one s- and three p- electron orbitals. Silicon, germanium and grey tin share the diamond-type structural arrangement.

Diamond is the high-pressure polymorph of carbon, and at low pressures or temperatures is thermodynamically unstable with respect to graphite. In nature, diamond is formed only at high pressures. Kimberlites, the primary source rocks for diamonds, are intrusions of carbon dioxide rich ultrabasic igneous magmas. Erosion of these intrusions yields alluvial, or placer, diamond deposits, a common source for this mineral.

The CHIME figure shows carbons as grey spheres. The unit cell is outlined. Note the tetrahedral coordination of each carbon.