Ringwoodite is a high-pressure polymorph of olivine (a magnesium iron silicate) that is formed at high temperatures and pressures of the Earths mantle between 525 and 660 km depth. Ringwoodite is notable for being able to contain hydroxide ions (oxygen and hydrogen atoms bound together) within its structure.[4] Combined with evidence of its occurrence deep in the Earths mantle, this suggests that there is from one to three world oceans equivalent of water in the mantle transition zone from 410 to 660 km deep.[5][6] This mineral was first identified in the Tenham meteorite in 1969,[7] and it is inferred to be present in large quantity in the Earth’s mantle. Ringwoodite was named after the Australian earth scientist Ted Ringwood (1930–1993), who studied polymorphic phase transitions in the common mantle minerals olivine and pyroxene at pressures equivalent to depths as great as about 600 km. Olivine, wadsleyite, and ringwoodite are polymorphs found in the upper mantle of the earth. At depths greater than about 660 km, other minerals, including some with the perovskite structure, are stable. The properties of these minerals determine many of the properties of the mantle. en.wikipedia.org/wiki/Ringwoodite
Posted on: Tue, 02 Sep 2014 02:15:16 +0000
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