corundum, ruby, sapphire, history.1, India.12, properties.3, chemistry.2, gems

An early crystallographic study of corundum by the French mineralogist Jacques-Louis, Comte de Bournon, describing specimens from the East Indies and China. Bournon examines the external forms, modifications and geometrical relationships of corundum crystals, providing detailed descriptions accompanied by crystallographic figures. The paper helped clarify the characteristic crystal forms of corundum at a time when its relationship to ruby, sapphire and other exceptionally hard stones was still being established. Closely associated with Greville’s contemporary investigations of corundum, the study is an important contribution to the application of crystallography to gemstone identification and to the recognition of corundum as a distinct mineral species.