Growth history of a natural octahedral diamond

Abstract

Stratigraphical etch patterns obtained on diamond surfaces are shown to reveal structure within the diamond. A study has been made of the complex structure of an octahedral diamond by examining eleven successive polished cubic sections. This exposes the growth history of the diamond. The etch patterns on the opposite surfaces of a thin slab of the diamond and an ultra-violet absorption micrograph show a remarkable degree of correlation. It has been possible to identify the richly etched and lighter etched regions of the crystal as type I and type II diamond respectively. A strain pattern found within the diamond is shown to be related to the distribution of the two types of diamond and it is suggested that this strain may indicate that there exists a difference in the elastic properties of the two types of diamond. A brief analysis of some of the detailed structure within the diamond strongly indicates that solution and re-growth mechanisms have taken place successively to a very marked degree. Growth has evidently been in layers which do not always lie in crystallographic planes with simple indices.