Mugearite () is a type of

oligoclase Oligoclase is a rock-forming mineral belonging to the plagioclase feldspars. In chemical composition and in its crystallographic and physical characters it is intermediate between albite ( Na Al Si3 O8) and anorthite ( CaAl2Si2O8). The albite ...

-bearing

basalt Basalt (; ) is an aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the surface of a rocky planet or moon. More than 90 ...

, comprising

olivine The mineral olivine () is a magnesium iron silicate with the chemical formula . It is a type of nesosilicate or orthosilicate. The primary component of the Earth's upper mantle, it is a common mineral in Earth's subsurface, but weathers quickl ...

, apatite, and opaque oxides. The main

feldspar Feldspars are a group of rock-forming aluminium tectosilicate minerals, also containing other cations such as sodium, calcium, potassium, or barium. The most common members of the feldspar group are the ''plagioclase'' (sodium-calcium) felds ...

in mugearite is oligoclase. Mugearite is a

sodium Sodium is a chemical element with the symbol Na (from Latin ''natrium'') and atomic number 11. It is a soft, silvery-white, highly reactive metal. Sodium is an alkali metal, being in group 1 of the periodic table. Its only stable ...

-rich member of the

alkaline magma series The alkaline magma series is a chemically distinct range of magma compositions that describes the evolution of an alkaline mafic magma into a more evolved, silica-rich end member. Geochemical characterization Rocks in the alkaline magma series a ...

. In the

TAS classification The TAS classification can be used to assign names to many common types of volcanic rocks based upon the relationships between the combined alkali content and the silica content. These chemical parameters are useful, because the relative proportio ...

of volcanic rock, mugearite is classified as sodium-rich basaltic trachyandesite.

Examples

Western Scotland

Mugearite was first identified at Mugeary on the island of Skye, Scotland by

Alfred Harker Alfred Harker FRS (19 February 1859 – 28 July 1939) was an English geologist who specialised in petrology and interpretive petrography. He was Lecturer in Petrology at the University of Cambridge for many years, and carried out field mapping ...

in 1904.

Outcrop An outcrop or rocky outcrop is a visible exposure of bedrock or ancient superficial deposits on the surface of the Earth. Features Outcrops do not cover the majority of the Earth's land surface because in most places the bedrock or superficia ...

s of mugearite also occur on the island of

Mull Mull may refer to: Places *Isle of Mull, a Scottish island in the Inner Hebrides ** Sound of Mull, between the Isle of Mull and the rest of Scotland * Mount Mull, Antarctica *Mull Hill, Isle of Man * Mull, Arkansas, a place along Arkansas Highway ...

. These examples of mugearite were formed during a period of continental

flood basalt A flood basalt (or plateau basalt) is the result of a giant volcanic eruption or series of eruptions that covers large stretches of land or the ocean floor with basalt lava. Many flood basalts have been attributed to the onset of a hotspot reac ...

volcanic activity that happened in western Scotland during the Paleogene

period Period may refer to: Common uses * Era, a length or span of time * Full stop (or period), a punctuation mark Arts, entertainment, and media * Period (music), a concept in musical composition * Periodic sentence (or rhetorical period), a concept ...

of the Earth's geological history, when the North Atlantic Ocean opened between Europe and North America.

Oceanic islands

Mugearite has been erupted by the volcanoes of some oceanic islands at hotspots. Examples are

Hawaii Hawaii ( ; haw, Hawaii or ) is a state in the Western United States, located in the Pacific Ocean about from the U.S. mainland. It is the only U.S. state outside North America, the only state that is an archipelago, and the only state ...

, Ascension Island, Saint Helena, Réunion,

Mauritius Mauritius ( ; french: Maurice, link=no ; mfe, label= Mauritian Creole, Moris ), officially the Republic of Mauritius, is an island nation in the Indian Ocean about off the southeast coast of the African continent, east of Madagascar. It ...

and

Tahiti Tahiti (; Tahitian ; ; previously also known as Otaheite) is the largest island of the Windward group of the Society Islands in French Polynesia. It is located in the central part of the Pacific Ocean and the nearest major landmass is Austra ...

.https://www.tulane.edu/~sanelson/eens211/igneous_rocks_plate_tectonics.htm

Mars

Analysis of a

Martian Mars, the fourth planet from the Sun, has appeared as a setting in works of fiction since at least the mid-1600s. It became the most popular celestial object in fiction in the late 1800s as the Moon was evidently lifeless. At the time, the pr ...

rock found by the ''Curiosity'' rover and named "Jake Matijevic" (or "Jake M"), after a

NASA The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the US federal government responsible for the civil List of government space agencies, space program ...

engineer, determined that this Martian rock is very similar to mugearite erupted on Earth.

References

I. D. Muir and C. E. Tilley, ''Mugearites and Their Place in Alkali Igneous Rock Series,'' The Journal of Geology, Vol. 69, No. 2 (Mar., 1961), pp. 186-203
Aphanitic rocks Basalt {{Volcanology-stub