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False-color scanning electron microscope image of kimberlite from South Africa. Olivine crystals (green) are in a fine-grained matrix made up of clay minerals and carbonates (presented in blue, purple and buff colors). Kimberlite is an igneous rock and a rare variant of peridotite. It is most commonly known to be the main host matrix for diamonds.
Volcanic pipes are composed of a deep, narrow cone of solidified magma (described as "carrot-shaped"), and are usually largely composed of one of two characteristic rock types — kimberlite or lamproite. These rocks reflect the composition of the volcanoes' deep magma sources, where the Earth is rich in magnesium.
The volcanic rocks of the BHH and BM fields are classified as kimberlites. The ML rocks are not considered to be archetypal kimberilte and have been variously classified as alkaline ultramafic rocks, hybrid alkaline ultramafic rocks, alkali olivine basalt and basanite; they are difficult to classify because of strong clay alteration that has ...
The lamproite diamond source is unusual, as almost all diamonds are mined from kimberlite formations and from alluvial deposits of diamonds weathered from that "hardrock" source. The most prominent lamproite diamond source is the Argyle diamond mine in Australia. It is notable that the physical characteristics of Australian lamproite and the ...
The kimberlite is intruded into volcanic rocks of the Proterozoic Hemlock Formation. The exposed material is grayish green to reddish, iron stained highly weathered and consists of disaggregated rubbly fragments up to 10 inches (250 mm). It is generally accepted that the pipe was emplaced about 180 million years ago.
Deep beneath the BHH kimberlite field lies a 2.0 to 2.4 billion year old Precambrian craton called the Buffalo Head terrane, which has no exposure at surface.The Precambrian craton is overlain by about 1,600 m (5,200 ft) of Paleozoic and Mesozoic sedimentary rocks, which are covered by as much as 200 m (660 ft) of unconsolidated glacial and post-glacial sediments of Quaternary age.
The ML pipes form part of the Northern Alberta kimberlite province, along with the nearby Birch Mountains kimberlite field and the Buffalo Head Hills kimberlite field. They were discovered in 1989-90 just north of Mountain Lake (55.456291n 117.714510w), which lies about 75 km (47 mi) northeast of Grande Prairie, Alberta. The ML south pipe ...
The mine was the first successful commercial non alluvial diamond mine not located on a kimberlite pipe. The pipe is named "AK-1", although it is commonly simply called the "Argyle pipe". The volcanic pipe is a diatreme, composed of olivine lamproite, present as tuff and lava.