Age and origin of eclogitic diamonds from the Jwaneng kimberlite, Botswana

Abstract

The 240 Ma old Jwaneng DK2 kimberlite in southern Botswana, probably the most profitable diamond mine m the world, is otherwise notable in several respects. First, the kimberlite carries two generations of kimberlitic zircon, one equivalent to the age of emplacement and the other Archaean Second, a significant proportion of the diamonds are poly crystalline aggregates (Kirkley et al, 1994) as well as cubic or fibrous forms with micro inclusions representing mantle fluids Third, the majority of macro inclusion bearing diamonds are eclogitic