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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.
Such rocks typically contain less than 45% silica. Ultramafic rocks are further classified by their relative proportions of olivine, orthopyroxene, clinopyroxene, and hornblende, which are the most abundant families of mafic minerals in most ultramafic rocks. Peridotite is then defined as coarse-grained ultramafic rock in which olivine makes up ...
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'.
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 ...
Wehrlite is an ultramafic and ultrabasic rock that is a mixture of olivine and clinopyroxene. It is a subdivision of the peridotites. The nomenclature allows up to a few percent of orthopyroxene. Accessory minerals include ilmenite, chromite, magnetite and an aluminium-bearing mineral (plagioclase, spinel or garnet). [1]
Pages in category "Ultramafic rocks" The following 15 pages are in this category, out of 15 total. This list may not reflect recent changes. ...
[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.
Serpentine soil is an uncommon soil type produced by weathered ultramafic rock such as peridotite and its metamorphic derivatives such as serpentinite. More precisely, serpentine soil contains minerals of the serpentine subgroup, especially antigorite, lizardite, and chrysotile or white asbestos, all of which are commonly found in ultramafic ...