Chromian spinel exsolution in ilmenite from the Premier Mine,Transvaal, South Africa

Exsolution intergrowths of a chrome rich spinel are reported for the first time in terrestrial ilmenite. The ilmenite in which this phenomenon has been observed occurs in the Premier Diamond Mine kimberlite. The occurrence is also noteworthy for the reasons that exsolution textures of any nature are extremely rare in ilmenite derived from kimberlite, and because the exsolved spinel has no known terrestrial counterpart, but is remarkably similar in chemical composition to certain lunar chromian ulvöspinels.