Majorite

Majorite is a type of mineral found in the upper mantle of the Earth. Its chemical formula is Mg₃(Fe,Al,Si)₂(SiO₄)₃. Majorite was first described from the Coorara Meterorite of Western Australia and has been reprted from various other meteorites.^[1][2] Mantle derived xenoliths containing majorite have been reported from potassic ultramafic magmas on Malaita Island on the Ontong Java Plateau Southwest Pacific.^[3]

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A significant property of majorite is that under conditions of high pressure and temperature as exist in the mantle the mineral tends to absorb and store oxygen. However when the temperature and pressure decrease as would occur when the majorite is drawn up toward the surface of the Earth by convection currents the mineral breaks down and releases the oxygen. Recent research has suggested that the total amount of oxygen stored in majorite in the mantle is likely quite large and may in fact contribute to keeping the earth's surface moist and inhabitable.^[4]

References

1. ^ http://www.mindat.org/min-2546.html Majorite on MinDat
2. ^ http://rruff.geo.arizona.edu/doclib/hom/majorite.pdf Mineral Data Publishing
3. ^ http://www.sciencemag.org/cgi/content/abstract/288/5469/1215 Kenneth D. Collerson, et. al., Rocks from the Mantle Transition Zone: Majorite-Bearing Xenoliths from Malaita, Southwest Pacific, Science 19 May 2000: Vol. 288. no. 5469, pp. 1215 - 1223
4. ^ Bryner, Jeanna: Huge Stockpile of Oxygen Found Deep Inside Earth, LiveScience, 01 October 2007 08:38 am ET[1]