igneous
Kimberlite
Kimberlite (Potassic ultramafic volcanic rock)
Hardness: 6-7 (matrix); Color: dark gray, bluish-green, or brownish; Luster: dull to greasy; Crystal Structure: Porphyritic matrix; Specific Gravity: 2.7-3.3.
- Hardness
- 6-7 (matrix)
- Color
- dark gray, bluish-green, or brownish
- Luster
- dull to greasy
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Physical properties
Hardness: 6-7 (matrix); Color: dark gray, bluish-green, or brownish; Luster: dull to greasy; Crystal Structure: Porphyritic matrix; Specific Gravity: 2.7-3.3.
Formation & geological history
Formed through high-pressure volcanic eruptions originating in the Earth's mantle, traveling through 'pipes' to the surface. Most are 70 to 150 million years old.
Uses & applications
The primary source of natural diamonds. It is also studied for mantle research and as a collector's specimen.
Geological facts
Named after Kimberley, South Africa. It is the 'mother rock' of most diamonds found on Earth, transporting them from depths of over 150 kilometers.
Field identification & locations
Identify by its 'Blue Ground' appearance when fresh or 'Yellow Ground' when weathered, often containing large noticeable crystals (phenocrysts) like olivine or phlogopite. Found in cratons like those in South Africa, Canada, and Russia.
