* Astronomy

Blobrana · L

RE: Tranquillityite

Blobrana · L

Title: Tranquillityite: The last lunar mineral comes down to Earth
Authors: Birger Rasmussen, Ian R. Fletcher, Courtney J. Gregory, Janet R. Muhling and Alexandra A. Suvorova

Tranquillityite [Fe2+8(ZrY)2Ti3Si3O24] was first discovered in mare basalts collected during the Apollo 11 lunar mission to the Sea of Tranquillity. The mineral has since been found exclusively in returned lunar samples and lunar meteorites, with no terrestrial counterpart. We have now identified tranquillityite in six dolerite dikes and sills from Western Australia. Terrestrial tranquillityite commonly occurs as clusters of fox-red laths closely associated with baddeleyite and zirconolite in quartz and K-feldspar intergrowths in late-stage interstices between plagioclase and pyroxene. Its composition is relatively uniform, comprising mostly Si, Zr, Ti, and Fe, with minor Al, Mg, Mn, Ca, Nb, Hf, Y, and rare earth elements. Its habit and chemistry are consistent with tranquillityite in lunar basalts, and it has a face-centered-cubic subcell, similar to that of annealed lunar tranquillityite. Unlike coexisting baddeleyite and zirconolite, it is commonly altered to a secondary intergrowth of submicron phases comprising mainly Si, Ti, and Ca, with minor Zr. In situ sensitive high-resolution ion microprobe (SHRIMP) U-Pb geochronology of tranquillityite from sills intruding the Eel Creek Formation, northeastern Pilbara Craton, yields a 207Pb/206Pb age of 1064 ± 14 Ma.

Blobrana · L

Rare moon mineral found in Australia

Australian scientists have discovered a rare mineral previously known only to be found in lunar rock samples and used it to date an Earth rock which formed over a billion years ago.
Named tranquillityite after the Sea of Tranquility, where astronauts landed on the Moon in 1969, researchers discovered the substance in rocks collected from six sites in Western Australia.
Tranquillityite was first discovered in rocks brought back from the moon soon after the first Apollo mission, along with two other substances - armalcolite and pyroxferroite. Both substances were found in Earth rocks within a decade or so of the 1969 Apollo mission but the third, tranquillityite, wasn't found on Earth until now.
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