igneous

Diamond in Kimberlite

Diamond (C in Kimberlite Matrix)

Hardness: 10 (diamond), 6-7 (matrix); Color: Colorless to white (diamond), green-gray to brown (matrix); Luster: Adamantine (diamond), earthy to greasy (matrix); Crystal structure: Isometric (diamond); Specific gravity: 3.5 (diamond), 2.2-3.0 (matrix).

Hardness: 10 (diamond), 6-7 (matrix)
Color: Colorless to white (diamond), green-gray to brown (matrix)
Luster: Adamantine (diamond), earthy to greasy (matrix)

Identified May 19, 2026More igneous →

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Physical properties

Formation & geological history

Formed at extreme depths in the Earth's mantle (over 150 km) under high pressure and temperature. Transported to the surface by rapid, explosive volcanic eruptions called kimberlite pipes millions or billions of years ago.

Uses & applications

Primary source for gemstone diamonds used in jewelry; industrial diamonds used for cutting, grinding, and drilling bits; highly valuable for geological research and mineral collecting.

Geological facts

Kimberlite is named after the town of Kimberley in South Africa. Diamonds are the only gemstones made of a single element (Carbon). Most diamonds seen in matrix like this are over 1 billion years old.

Field identification & locations

Identify by a small, greasy-looking glassy octahedron or form embedded in a dark, ultra-mafic brecciated rock. Found almost exclusively in ancient stable continental cratons like those in South Africa, Russia, Canada, 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