Abstract
Micro-inclusions in diamonds from Zaire and Botswana differ in composition from the more common large inclusions of the peridotitic or eclogitic assemblages. These sub-micrometre inclusions resemble potassic magmas in their composition, but are enriched in H2O, CO2-3 and K2O and depleted in MgO. This composition represents a volatile-rich fluid or melt from the upper mantle, which was trapped in the diamonds as they grew. © 1988 Nature Publishing Group.