Sentence examples for kimberlites from inspiring English sources

Not all kimberlites contain diamonds.

For example, it occurs in some peridotites, especially those called kimberlites, which are the rocks in which diamonds occur.

Two other rare occurrences in cratonic (stable) areas of the Earth's crust are the kimberlites and carbonatites.

Kimberlites are mica peridotites that are found in pipes.

Most carbonatites occur close to intrusions of alkaline igneous rocks (those rich in potassium or sodium relative to their silica contents) or to the ultramafic igneous rocks (rocks with silica contents below approximately 50 percent by weight) known as kimberlites and lamproites.

The alluvial terraces are exhausted and the future lies in the underlying kimberlite rock.

This is good news for the mine's 1,000 or so employees and for the town, which has depended on the diamond business since Sir Thomas Cullinan discovered a prospect there in 1898 that contained kimberlite, a rock that can be rich in diamonds.

The mine, established in 1903, is one of 30 or so kimberlite diamond mines in the world, and is believed to be still the world's second-most-valuable diamond resource.Petra is a relatively small outfit, listed on London's Alternative Investment Market, that specialises in buying mines that bigger companies see as marginal.

"Progress in Kono has not been commensurate with expectations," admits Ibrahim Kamara, who runs a kimberlite project for Koidu Holdings.Such are the growing pains of a nascent industry in a dirt-poor African country.

Angola has agreed to repay part of the money by awarding oil and diamond concessions to Russian firms.Almazy Rossii Sakha (Alrosa), a large Russian diamond company, is already involved in a big kimberlite mine in Catoca, in the north-east of the country.

Omphacite-bearing eclogite nodules are associated with peridotites in the kimberlite pipes of South Africa.