Peridotites are high-density, coarse-grained igneous rocks, formed mainly by the minerals Olivine and Pyroxene.
The name Peridotite comes from the gem Peridot, which is composed of light green Olivine.
Although they are mostly dark green rocks, peridotites can appear in different shades of yellow, brown, red and even blue, depending on the proportions of the minerals that compose them.
This is an ultramafic group of rocks, since they contain less than 45% of Silica (silicon oxide), being composed mainly of Magnesium (Mg) and iron oxides and characterized by their different proportions of Pyroxenes, Chromite, Plagioclase and Amphibolite.
Peridotites are the dominant rocks in the upper mantle of the earth, normally located at depths exceeding 200 kilometers and being difficult to find on the surface, as their main compounds degrade relatively easily in contact with air and water.
Peridotite outcrops in the earth's crust occur mainly in areas of continental subduction, where the collision of a tectonic plate against another has made them rise until they are exposed. They are of great scientific interest, since they provide data on the processes that occurred in the formation phase of our planet.
*Photo By Haroy Jean-Michel - Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=81392702
