High Pressure Mineralogy Minerals Methods Meaning Quart z

High Pressure Mineralogy Minerals Methods & Meaning

Quart z and its high pressure polymorphs, coesite and Quartz poly stishovite were first found made in the laboratory, and morp found hsin nature at the site of the Meteor Crater, AZ, later meteorite impact. Stishovite demonstrates that silicon can assume six-coordination SM Stishov www. hppi. troitsk. ru/products/stishovite 1. htm ruby. colorado. edu/~smyth/ min/tio 2. html Laboratory studies also indicated that high pressure polymorphs of other minerals could occur (e. g. , olivine, pyroxene, garnet). High pressure phases of other minerals were historically first found in nature in meteorites.

Early work on Ni Early (1950’s) studies of germanate systems indicated that phase changes could occur. Ni 2 Ge. O 4 (olivine) pressure Ni 2 Ge. O 4 (spinel) Later work showed that silicates underwent the same phases changes but at higher pressures: Ni 2 Si. O 4 (olivine) Ni 2 Si. O 4 (spinel) 55 kbar, ° 1400 C

Color changes were observed in minerals at pressure High pressure effects indicating that the bonding was changing as well as the density. Olivine becomes black at 270 kbar Laboratory chemicals change oxidation state (Fe 3+ Fe 2+) Seismic velocities suddenly change at 410 and 660 km in the earth

Wadsle yite A new polymorph of olivine was found in the Peace River meteorite. It has a modified spinel structure that was called the b-spinel structure. It was given the mineral name, wadsleyite. http: //www. geo. ucalgary. ca/cdnmeteorites/meteorite/peaceriver 1. html Wadsleyite was first discovered in the Peace River stonemeteorite (ordinary chondrite L 6) that fell at Peace River, Alberta, Canada. 31 March 1963 Wadsley

Ringwoodite Another polymorph of Mg 2 Si. O 4 was found in the Siziangkou (China) and other meteorites. It has the spinel structure. It is named ringwoodite. A. E. (Ted) Ringwoodite in the Tenham Meteorite. (Stöffler et al. ) www. science. org. au/academy/ memoirs/rgwd. htm Ringwoodite in impact glass from Spain. (Glazovskaya et al. )

olivine, polymorphs Mg 2 Si. O 4 g-spinel ringwoodite b-spinel wadsleyite

Rockland piston-cylinder system: 250 ton press Piston-cylinder high pressure Institute for High Pressure Physics, Russian Academy of Sciences

Diamond Cell Diamond cell used for high pressure experiments. Hemley (1997), Geophysical Laboratory, Carnegie Institution of Washington www. geo. lsa. umich. edu/~crib/COURSES/117/Lect 17. html

Extremely high Shock wave lab pressure can be generated through shockimpact, but for only nanoseconds at a time. Caltech’s shock wave lab Pressure in excess of 1. 5 Mbar can be achieved.

Ringwoo dite to perovskit e At in laboratory experiments at high pressures ringwoodite breaks down to form a perovskite. g-Mg 2 Si. O 4 spinel ringwoodite Silicate perovskite may occupy enormous volumes in the earth’s lower mantle. It may be the most abundant mineral in planet earth! (Mg, Fe)Si. O 3 perovskite Silicate perovskite + (Mg, Fe)O periclase (magnesiowustite)

Majorite Orthopyroxene transforms at high pressure to the garnet structure. 2 (Mg, Fe)2 Si 2 O 6 Mg 3(Fe, Si)2(Si. O 4)3 The high pressure phase was first found at Coorara meteorite crater, Rawlina, Western Australia, Australia. It is also found in other meteorites The natural mineral is named majorite. (1970)

Tenham meteorite with akimotoite The Tenham meteorite that contains akimotoite, (Mg, Fe)Si. O 3 , of the ilmenite structure and other high pressure minerals. Orthopyroxene -> majorite-garnet -> silicate-perovskite -> akimotoite

Akimotoite in Tenham chondrite. Akimotoite, (Mg, Fe)Si. O 3 , a mineral of the ilmenite group, was found in the shockmetamorphosed Tenham chondrite. Natural occurrence of Mg. Si. O 3 -ilmenite perovskite in a shocked L 5 -6 chrondrite. Sharp TG, Lingemann CM, Dupas C, Stöffler D Lunar and Planetary Science XXVIII

World's deepest rocks recovered BBC News, 19 -May-2000 They were found at the Earth's surface on the island of Malaita, east of Papua New Guinea. But they originate from deep within the planet, between 400 km and 670 km down. Professor Ken Collerson, from Queensland University, has shown that the most abundant mineral, garnet, contains a majorite component. Majorite = Mg 3(Fe, Si)2(Si. O 4)3

Diamond Inclusions in diamonds bring up samples from the earth’s upper mantle Kelsie Dadd, www. es. mq. edu. au/gemoc/annrep 1998/ Reshighlights 98. htm Mark Rivers www-fp. mcs. anl. gov/xray-cmt/rivers/ diamonds. html Jill Banfield, http: //www. geology. wisc. edu/~jill/jpeg/l 6 sj 2. jpeg

Determine the Phases in the Deep Earth Combine data from natural inclusions with laboratory studies

Olivine Depth phases vs. depth Pressure olivine 135 kbar 410 km wadsleyite b-spinel ringwoodite g-spinel 230 kbar 660 km (Mg, Fe)Si. O 3 + (Mg, Fe)O perovskite periclase akimotoite ? ilmenite

Earth Model 10 kbar = l GPa From Stöffer (1997)

Silicate Perovskite Is this the most important mineral in the Earth?