igneous

Kimberlite

Kimberlite (Group I or II)

Hardness: 6-7 (matrix); Color: Dark bluish-gray to greenish-black (serpentinized); Luster: Dull to greasy; Structure: Porphyritic, containing phenocrysts of olivine, phlogopite, and pyrope garnet; Specific Gravity: 2.7–3.3

Hardness: 6-7 (matrix)
Color: Dark bluish-gray to greenish-black (serpentinized)
Luster: Dull to greasy

Identified May 19, 2026More igneous →

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Physical properties

Formation & geological history

Formed at extreme depths (greater than 150km) in the Earth's mantle and brought to the surface through deep-seated volcanic eruptions called kimberlite pipes. These eruptions are rare and incredibly fast-moving.

Uses & applications

The primary source of industrial and gemstone diamonds. Also studied by geologists to understand mantle composition and ancient plate tectonics.

Geological facts

Named after the town of Kimberley, South Africa, where a massive diamond rush occurred in the 1870s. Only about 1 in 200 kimberlite pipes contain economic concentrations of diamonds.

Field identification & locations

Identified by its distinctive 'blue ground' or 'yellow ground' (weathered) appearance and the presence of 'indicator minerals' like chrome diopside and pyrope garnet. Found in ancient continental cratons (South Africa, Russia, Canada).

Other igneous specimens

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Blue Apatite

Fluorapatite (Ca5(PO4)3F)

mineral

Dark Igneous Rock (Likely Basalt or Diabase)

Basalt (extrusive igneous rock) or Diabase (intrusive igneous rock - also known as Dolerite), largely composed of plagioclase feldspar, pyroxene (augite), and sometimes olivine and amphibole. Exact mineralogy would require thin section analysis.

Igneous