Tranquillityite Explained
Tranquillityite |
Category: | Silicate mineral (nesosilicate group) |
Formula: | (Fe2+)8Ti3Zr2 Si3O24 |
Imasymbol: | Trq[1] |
Strunz: | 9.AG.90 |
Dana: | 78.07.16.01 (Unclassified silicates) |
System: | Hexagonal Unknown space group |
Unit Cell: | a = 11.69, c = 22.25 [Å] Z = 6; V = 2,633.24 Å3 |
Color: | Gray, dark red-brown in transmitted light |
Habit: | Lath shaped grains generally found as inclusions in other minerals or interstitial (<0.1% in weight) |
Luster: | Submetalic |
Diaphaneity: | Opaque to semitransparent |
Opticalprop: | Biaxial |
Refractive: | nα = 2.120 |
2V: | 40° |
Pleochroism: | No |
Density: | 4.7 ± 0.1 g/cm3 |
Impurities: | Y, Hf, Al, Cr, Nb, Nd, Mn, Ca |
References: | [2] [3] [4] |
Tranquillityite is silicate mineral with formula (Fe2+)8Ti3Zr2 Si3O24. It is mostly composed of iron, oxygen, silicon, zirconium and titanium with smaller fractions of yttrium and calcium. It is named after the Mare Tranquillitatis (Sea of Tranquility), the place on the Moon where the rock samples were found during the 1969 Apollo 11 mission. It was the last mineral brought from the Moon which was thought to be unique, with no counterpart on Earth, until it was discovered in Australia in 2011.[5]
Discovery
In 1970, material scientists found a new unnamed Fe, Ti, Zr- silicate mineral containing rare-earths and Y in lunar rock sample 10047.[6] The first detailed analysis of the mineral was published in 1971 and the name "tranquillityite" was proposed and later accepted by the International Mineralogical Association.[7] It was later found in lunar rock samples from all Apollo missions. Samples were dated by Pb/Pb ion probe techniques.
Together with armalcolite and pyroxferroite, it is one of the three minerals which were first discovered on the Moon, before terrestrial occurrences were found.[2] [8] Fragments of tranquillityite were later found in Northwest Africa, in the NWA 856 Martian meteorite.
Terrestrial occurrences of tranquillityite have been found in six localities in the Pilbara region of Western Australia, in 2011. The Australian occurrences include a number of Proterozoic to Cambrian age diabase and gabbro dikes and sills. It occurs as interstitial grains with zirconolite, baddeleyite, and apatite associated with late stage intergrowths of quartz and feldspar.
Properties
Tranquillityite forms thin stripes up to 15 by 65 micrometres in size in basaltic rocks, where it was produced at a late crystallization stage. It is associated with troilite, pyroxferroite, cristobalite and alkali feldspar. The mineral is nearly opaque and appears dark red-brown in thin crystals. The analyzed samples contain less than 10% impurities (Y, Al, Mn, Cr, Nb and other rare-earth element) and up to 0.01% (100 ppm) of uranium. Presence of a significant amount of uranium allowed scientists to estimate the age of tranquillityite and some associated minerals in Apollo 11 samples as 3710 million years using the uranium–lead dating technique.
Irradiation by alpha particles generated by uranium decay is believed to be the origin of the predominantly amorphous metamict structure of tranquillityite. Its crystals were obtained by annealing the samples at for 30 minutes. Longer annealing did not improve the crystalline quality, and annealing at higher temperatures resulted in spontaneous fracture of samples.
The crystals were initially found to have a hexagonal crystal structure with the lattice parameters, a = 1.169 nm, c = 2.225 nm and three formula units per unit cell, but later reassigned a face-centered cubic structure (fluorite-like). A tranquillityite-like crystalline phase has been synthesized by mixing oxide powders in an appropriate ratio, determined from the chemical analysis of the lunar samples, and annealing the mixture at . This phase was not pure, but intergrown with various intermetallic compounds.
See also
References
- Citations
Bibliography
- Cameron. E. N.. Opaque minerals in certain lunar rocks from Apollo 11. Proceedings of the Apollo 11 Lunar Science Conference (5–8 January 1970, Houston, TX) . 1970. 1: Mineralogy and Petrology. Geochimica et Cosmochimica Acta Supplement. 193–206. 1970GeCAS...1..221C.
- Dence. M. R.. Douglas. J. A. V.. Plant. A. G. . Traill. R. J.. Petrology, Mineralogy and Deformation of Apollo 11 Samples. Proceedings of the Apollo 11 Lunar Science Conference (5–8 January 1970, Houston, TX) . 1970. 1: Mineralogy and Petrology. Geochimica et Cosmochimica Acta Supplement. 315–340. 1970GeCAS...1..315D.
- New mineral names. American Mineralogist. 1973. 58. 1–2. 139–141. Fleischer. Michael.
- Structural studies on tranquillityite and related synthetic phases. Gatehouse . B. M.. Grey . I. E.. Lovering . J. F.. Wark . D. A.. Proceedings of the Lunar Science Conference, 8th, Houston, Tex., March 14–18, 1977 . 2 (A78-41551 18–91). Pergamon Press, Inc.. 1977. 1831–1838. 1977LPSC....8.1831G. . New York.
- Book: Heiken. Grant. Lunar Sourcebook : a User's Guide to the Moon. 1991. Cambridge Univ. Press. Cambridge. 978-0-521-33444-0. 133–134. David. Vaniman . Bevan M. . French. 7 January 2012.
- Hinthorne. J.R.. Andersen . C.A. . Conrad . R.L . Lovering . J.F.. Single-grain 207Pb/206Pb and U/Th age determinations with a 10-micron spatial resolution using the ion microprobe mass analyzer (IMMA). Chem. Geol.. 1979. 25. 4. 271–303 . 10.1016/0009-2541(79)90061-5 . 1979ChGeo..25..271H.
- Leroux. Hugues. Cordier. Patrick. Magmatic cristobalite and quartz in the NWA 856 Martian meteorite. Meteoritics & Planetary Science. 41. 913923. 2006. 10.1111/j.1945-5100.2006.tb00495.x. 6. 2006M&PS...41..913L.
- Lovering. J. F.. Wark. D. A. . Reid. A. F.. Ware . N. G.. Keil. K.. Prinz. M.. Bunch. T.E.. El Goresy. A.. Ramdohr. P. . Brown. G. M.. Peckett. A.. Phillips. R.. Cameron. E. N.. Douglas. J. A. V.. Plant. A. G.. Tranquillityite: A new silicate mineral from Apollo 11 and Apollo 12 basaltic rocks. Proceedings of the Lunar Science Conference. 1971. 2. 39–45. 1971LPSC....2...39L. . 9.
- Ramdohr. Paul. El Goresy. Ahmed. Opaque Minerals of the Lunar Rocks and Dust from Mare Tranquillitatis. Science. 30 January 1970. 167. Ahmed. 3918. 615–618. 10.1126/science.167.3918.615. 17781517. 1970Sci...167..615R. 27627972.
- Rasmussen. Birger. Fletcher. Ian R.. Muhling. Janet R.. Pb/Pb Geochronology, Petrography and Chemistry of Zr-rich Accessory Minerals (Zirconolite, Tranquillityite and Baddeleyite) in Mare Basalt 10047. Geochimica et Cosmochimica Acta. 72. 5799–5818. 2008. 10.1016/j.gca.2008.09.010 . 2008GeCoA..72.5799R. 23.
- Rasmussen. Birger. Fletcher. Ian R.. Gregory. Courtney J.. Muhling. Janet R.. Suvorova. Alexandra A.. 10.1130/G32525.1. Tranquillityite: The last lunar mineral comes down to Earth . 2012. Geology. 40. 83–86. 1. . 2012Geo....40...83R.
- 10.1111/j.1945-5100.2002.tb00913.x. The Meteoritical Bulletin N°86 2002 July. 2002. Russell. Sara S.. Sara Russell . Zipfel. Jutta. Grossman. Jeffrey N.. Grady. Monica M.. Meteoritics & Planetary Science. 37. S5. A157–A184. . 2002M&PS...37..157R. 129570004 .
- Book: Walker. Robert M.. Nuclear tracks in solids : principles and applications. 1975. University of California Press. Berkeley. 978-0-520-02665-0. 505. Tranquillityite.. Robert L. . Fleischer. P.. Buford Price. 7 January 2012.
External links
Notes and References
- Warr. L.N.. 2021. IMA–CNMNC approved mineral symbols. Mineralogical Magazine. 85. 3. 291–320. 10.1180/mgm.2021.43. 2021MinM...85..291W. 235729616. free.
- Web site: Tranquillityite. Mindat.org. 2010-08-07.
- Web site: Tranquillityite. Webmineral. 2010-08-07.
- http://rruff.geo.arizona.edu/doclib/hom/tranquillityite.pdf Handbook of Mineralogy
- News: Rare Moon mineral found in Australia. ABC News. 5 January 2012. 15 January 2021.
- Web site: Meyer. Charles. NASA Lunar Sample Compendium. 2009. Nasa. Sample 10047:Ilmenite Basalt (low K) 138 grams Figure. 7 January 2012.
- Web site: Nickel. Ernest H.. Nichols. Monte C.. The official IMA-CNMNC List of Mineral Names. Commission on New Minerals, Nomenclature And Classification. International Mineralogical Association. 7 January 2012. 2009. 26 June 2013. https://web.archive.org/web/20130626060238/http://pubsites.uws.edu.au/ima-cnmnc/IMA2009-01. dead.
- http://curator.jsc.nasa.gov/lunar/letss/Mineralogy.pdf Lunar Sample Mineralogy