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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 obliterated most of their original mineralogy.
Kimberlite occurs in the Earth's crust in vertical structures known as kimberlite pipes, as well as igneous dykes and can also occur as horizontal sills. Kimberlite pipes are the most important source of mined diamonds today. The consensus on kimberlites is that they are formed deep within Earth's mantle.
Lamproite pipes operate similarly to kimberlite pipes, except that the boiling water and volatile compounds contained in the magma act corrosively on the overlying rock, resulting in a broader cone of eviscerated rock (the ejection of this rock also forms a tuff ring, like kimberlite eruptions). This broad cone is then filled with volcanic ash ...
It is generally accepted that the pipe was emplaced about 180 million years ago. The lake Ellen Kimberlite is popular with rock hounds as the classic indicator minerals (pyrope, magnesian ilmenite and chrome diopside) for kimberlite are easily found in the material, though few are of gem quality and size. While there was considerable interest ...
Aerial view of the Moses Rock Dike diatreme in San Juan County, Utah [1] A diatreme , sometimes known as a maar-diatreme volcano, is a volcanic pipe associated with a gaseous explosion. When magma rises up through a crack in Earth's crust and makes contact with a shallow body of groundwater , rapid expansion of heated water vapor and volcanic ...
The rock is a dark-green peridotite (kimberlite) composed of serpentinized olivine and a number of accessory minerals, including phlogopite, pyrope, calcite, enstatite, magnesian ilmenite, and others. Xenoliths, mainly of shale, and igneous rock inclusions are abundant in the three intrusive bodies as described by William Brown in 1977. [1]
The Fort à la Corne kimberlite field is a 104- to 95-million-year-old diamond-bearing kimberlite field in east-central Saskatchewan, Canada. Its kimberlite pipes are among the most complete examples in the world, preserving maar -shaped craters .
The Chidliak Kimberlite Province is located in the Hall Peninsula of southern Baffin Island, Nunavut, Canada.The first kimberlite there was discovered in July 2008 during exploration conducted by BHP Billiton and Peregrine Diamonds Ltd.