Kimberlite

Kimberlite is a volatile-rich, ultramafic igneous rock formed by deep-sourced magma. Rapid ascent can carry diamonds and other mantle minerals to Earth’s surface.

Kimberlite magma: Molten material that crystallizes into kimberlite, commonly rich in carbon dioxide, water, and mantle-derived components. Gas exsolution helps drive the rapid ascent that can preserve diamonds.
Ultramafic rock: An igneous rock composed chiefly of ferromagnesian minerals and containing little silica. Kimberlite’s ultramafic character reflects its mantle-rich composition.
Mantle plume: A proposed upwelling of unusually hot mantle that can produce extensive intraplate volcanism. Kimberlite magmatism is often discussed against plume models, though its origins remain debated.
Diamond exploration: The search for economically recoverable diamond deposits using geological, geochemical, and geophysical evidence. Kimberlite pipes are primary targets in much hard-rock diamond exploration.
De Beers: A multinational diamond company founded in the nineteenth century in southern Africa. Kimberlite discoveries in the region underpinned the rise of its diamond industry.
Volatile exsolution: The separation of dissolved gases from magma as pressure falls during ascent. Expanding volatiles can contribute to kimberlite’s rapid, explosive emplacement.
Carbon dioxide: A colorless gas and carbon-bearing compound that is a major volatile in many kimberlites. Its abundance helps distinguish kimberlite magmas and contributes to explosive ascent.
Subduction: The descent of one tectonic plate beneath another into Earth’s mantle. Recycled materials from subduction may contribute to some kimberlite source regions.
Indicator mineral: A mineral whose presence and composition help identify a particular geological source or process. Kimberlite indicator minerals can reveal concealed pipes through transported sediment.
Cullinan Diamond: A large rough diamond discovered in South Africa’s Premier Mine in 1905. It came from a diamond-bearing kimberlite pipe and illustrates the deposits’ potential.

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