A picture of the geometric coordination along the (110)-plane in brucite is shown below.
Each hydrogen atom forms a common face with the oxygen of the hydroxy-group and a smaller face with the oxygen of the hydroxy-group in the next layer. In addition several geometric coordinations to hydrogen and magnesium can be seen. As the hydrogen lies on a three-fold axis, the complete coordination geometric coordination is given below:
This gives a total geometric coordination number of 22 which is reduced to a chemical coordination number of 4. For Ca(OH)2 and under pressure slightly different coordinations may be result with the chemical coordination number rising to 5. But the 4 above described hydrogen bonds are stable in all brucite-like structures and over the whole pressure range.
Last Updated: 26 October 1996