igneous

Kimberlite

Kimberlite (Potassic ultramafic igneous rock)

Hardness: 6-7 on Mohs scale; Color: Blue-gray to green-gray (often called 'blue ground'); Luster: Dull to greasy; Crystal Structure: Porphyritic texture with phenocrysts of olivine; Cleavage: None (conchoidal fracture); Specific Gravity: 2.7 - 3.3.

Hardness: 6-7 on Mohs scale
Color: Blue-gray to green-gray (often called 'blue ground')
Luster: Dull to greasy

Identified May 18, 2026More igneous →

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Physical properties

Formation & geological history

Formed through deep-seated volcanic eruptions (kimberlite pipes) originating from the Earth's mantle (150-450 km deep). These occur in ancient stable continental crust (cratons), primarily during the Mesozoic and Cenozoic eras.

Uses & applications

Primary source of natural diamonds. Significant for scientific research regarding mantle composition and deep-earth tectonics.

Geological facts

Kimberlite is the world's most important source of diamonds. It is named after the town of Kimberley in South Africa, where a massive rush followed the discovery of an 83.5-carat diamond in 1871.

Field identification & locations

Identify by its 'brecciated' or fragmented appearance and dark spots of olivine and phlogopite. Found in 'pipes' or vertical dikes. Major locations include South Africa, Russia (Siberia), Canada (Yellowknife), and Australia.

Other igneous specimens

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Blue Apatite

Fluorapatite (Ca5(PO4)3F)

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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

Magnetite

Iron(II,III) oxide (Fe3O4)

mineral

Sodalite

Sodalite - Na8(Al6Si6O24)Cl2

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Blue Apatite

Apatite (Group), Ca5(PO4)3(F,Cl,OH)

mineral

Magnetite

Magnetite (Fe3O4)

mineral