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