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Volcanic ultramafic rocks are rare outside of the Archaean and are essentially restricted to the Neoproterozoic or earlier. Subvolcanic ultramafic rocks and dykes persist longer, but are also rare. There is evidence of ultramafic rocks elsewhere in the solar system. Examples include komatiite [2] and picritic basalt.
Lherzolite – an ultramafic and ultrabasic rock that is composed of olivine and pyroxene – An ultramafic rock, essentially a peridotite Monzogranite – Biotite granite rocks that are considered to be the final fractionation product of magma – A silica-undersaturated granite with <5% normative quartz
Dun Mountain was given its name because of the dun colour of the underlying ultramafic rocks. This color results from surface weathering that oxidizes the iron in olivine in temperate climates (weathering in tropical climates creates a deep red soil). The dunite from Dun Mountain is part of the ultramafic section of the Dun Mountain Ophiolite Belt.
[7] [16] The Bushveld igneous complex, South Africa is an example of a system displaying both of these structures. [17] Cut drill core displaying massive sulfide within an ultramafic rock. The massive sulfide is primarily composed of pyrrhotite with trace amounts of chalcopyrite and pentlandite.
Komatiite / k oʊ ˈ m ɑː t i ˌ aɪ t / is a type of ultramafic mantle-derived volcanic rock defined as having crystallised from a lava of at least 18 wt% magnesium oxide (MgO). [1] It is classified as a 'picritic rock'.
Pages in category "Ultramafic rocks" The following 15 pages are in this category, out of 15 total. This list may not reflect recent changes. ...
Serpentinite is a metamorphic rock composed predominantly of serpentine group minerals formed by serpentinization of mafic or ultramafic rocks. The ancient origin of the name is uncertain; it may be from the similarity of its texture or color to snake skin. [1] Greek pharmacologist Dioscorides (AD 50) recommended eating this rock to prevent ...
A rock with over 90% mafic mineral content will be classified instead as an ultramafic rock. A gabbroic rock with less than 10% mafic mineral content will be classified as an anorthosite. [8] [13] A more detailed classification is based on the relative percentages of plagioclase, pyroxene, hornblende, and olivine. The end members are: [8] [13]