Lamproite

Lamproite is a peralkaline volcanic rock. Olivine lamproite pyroclastic rocks and dikes are sometimes hosts for diamonds. The diamonds occur as xenocrysts that have been carried to the surface or to shallow depths by the lamproite diapiric intrusions.

Related Topics:
Peralkaline - Volcanic rock - Olivine - Pyroclastic - Dikes - Diamond - Xenocryst - Diapir - Intrusion

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Lamproites occupy relatively shallow bowl shaped craters up to 1.5 km in diameter and about 300 m in depth.

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Minerals typical of lamproites include:

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forsteritic olivine; high iron leucite; titanium-rich aluminium-poor phlogopite; potassium- and titanium-rich richterite; low aluminium diopside; and iron-rich sanidine. A variety of rare trace minerals occur. The rocks are high in potassium with 6 to 8% potassium oxide. High chromium and nickel content is typical. The rocks commonly are altered to talc with carbonate or serpentine, chlorite, and magnetite. Zeolites and quartz may also occur.

Related Topics:
Forsteritic - Iron - Leucite - Titanium - Aluminium - Phlogopite - Potassium - Richterite - Diopside - Sanidine - Potassium oxide - Chromium - Nickel - Talc - Carbonate - Serpentine - Chlorite - Magnetite - Zeolite - Quartz

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Lamproites form from partially melted mantle at depths exceeding 150 km. The molten material is forced to the surface in volcanic pipes, bringing with it xenoliths and diamonds from the harzburgitic peridotite or eclogite mantle regions where diamond formation is stabilized.

Related Topics:
Mantle - Volcanic pipe - Xenolith - Harzburgitic - Peridotite - Eclogite

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The economic significance of lamproite became known with the 1979 discovery of the Argyle diamond pipe in Western Australia. This discovery led to the intense study and re-evaluation of other known lamproite occurrences worldwide; previously only kimberlite pipes were considered economically viable sources of diamonds.

Related Topics:
1979 - Argyle diamond pipe - Western Australia - Kimberlite

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The Argyle diamond mine remains the only economically viable source of lamproite diamonds. This deposit differs markedly by having a high content of diamonds but low quality of most of stones. Research at Argyle diamond have shown that most of stones are of E-type, they originate from eclogite source rocks and were formed under high temperature ~1400 °C. The Argyle diamond mine is the main source of rare pink diamonds.

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The diamonds of Crater of Diamonds State Park near Murfreesboro, Arkansas are found in a lamproite host.

Related Topics:
Crater of Diamonds - Murfreesboro, Arkansas

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