Tranquilityite

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Tranquilityite
General and classification
other names

IMA 1971-013

chemical formula Fe 8 2+ Ti 3 (Zr, Y) 2 [O 12 | (SiO 4 ) 3 ]
Mineral class
(and possibly department) 		Silicates and Germanates
System no. to Strunz
and to Dana 		9.AG.90 ( 8th edition : VIII / B.07)
78.07.16.01
Crystallographic Data
Crystal system hexagonal
Crystal class ; symbol Please complete!
Lattice parameters a  = 11.69  Å ; c  = 22.25 Å
Formula units Z  = 3
Physical Properties
Mohs hardness not defined
Density (g / cm 3 ) calculated: 4.7 ± 0.1
Cleavage Please complete!
colour gray, dark red-brown in transmitted light
Line color Please complete!
transparency opaque to translucent
shine semi-metallic
Crystal optics
Refractive indices n α  = 2.120
Birefringence δ = 2.120
Optical character biaxial
Axis angle 2V = 40 ° (measured)

Tranquilityite is a very rare mineral from the mineral class of " silicates and germanates ". It crystallizes in a hexagonal crystal system with the composition Fe 8 2+ Ti 3 (Zr, Y) 2 [O 12 | (SiO 4 ) 3 ], so it is chemically an island silicate with oxygen as additional anions as well as iron , titanium and zirconium or smaller amounts of yttrium , which can replace the zirconium diadoch .

Etymology and history

It is named after the Mare Tranquillitatis ( sea ​​of ​​calm ) on the moon , where the rock samples in which the mineral was later discovered were collected during the Apollo 11 mission in 1969 . It was the last mineral found on the moon that was thought to be unique; H. without occurrence on earth until it was also found in Australia in 2011 .

In 1970, materials scientists found an unknown silicate mineral in moon rock sample No. 10047, which contained iron, titanium and zirconium as well as rare earths . The first detailed analysis of the new mineral was published in 1971 and the proposed name tranquilityite was accepted by the International Mineralogical Association (IMA). It was later discovered to be found in the lunar rock samples from all Apollo missions.

classification

Already in the now outdated, but still common 8th edition of the mineral systematics according to Strunz , the tranquilityite belonged to the mineral class of "silicates and germanates" and there to the department of " island silicates with non-tetrahedral anions (Neso subsilicates)", of which it was the only member formed independent group VIII / B.07 .

The 9th edition of Strunz's mineral systematics , which has been in effect since 2001 and is used by the IMA, also assigns tranquilityite to the class of “silicates and germanates” and there in the “island silicates (nesosilicates)” category. This section is, however, further subdivided according to the possible presence of further anions and the coordination of the cations, so that the mineral is classified according to its composition in the subdivision of “Island silicates with additional anions; Cations in mostly [6] er and> [6] er coordination ”can be found, where it also forms the unnamed group 9.AG.90 without further members .

The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns tranquilityite to the class of "silicates and Germanates" and there in the department of "unclassified silicate minerals". Here he is the only member / together with in the unnamed group 78.07.16 within the sub-section "Unclassified Silicates: Completely Unclassified Silicates".

Crystal structure

Tranquilityite crystallizes hexagonally with the lattice parameters a  = 11.69  Å and c  = 22.25 Å and 3 formula units per unit cell .

properties

The samples analyzed contain less than 10% impurities (Y, Al, Mn, Cr, Nb and other rare earths) and up to 0.01% (100  ppm ) uranium . This amount of uranium made it possible to determine the age of tranquilityite and some associated minerals in Apollo 11 samples using the uranium-lead method as 3710 million years. It is assumed that the predominantly amorphous metamisk structure of tranquilityite is caused by alpha radiation from the decay of uranium.

The crystals were obtained by annealing the samples at 800 ° C. for 30 minutes. Prolonged annealing did not improve the crystal quality; annealing at higher temperatures led to spontaneous breakage of the samples. A tranquilityite-like crystalline phase has been synthesized by mixing oxide powders in the same proportion as in lunar rocks and annealing the mixture at 1500 ° C. The resulting phase was not pure, but interspersed with various intermetallic compounds .

Education and Locations

Tranquilityite forms thin strips of up to 15 by 65 micrometers in basaltic rocks, in which it is formed in a late crystallization phase. Tranquilityite is associated with troilite , pyroxferroit, cristobalite and alkali feldspars . It is almost opaque and appears as a thin crystal, dark red-brown.

Like armalcolite and pyroxferroit , tranquilityite was only found later on Earth, for example as a fragment in the Martian meteorite NWA 856 from northwest Africa. However, these particles do not originally come from Earth either.

It was not until 2011 that original earthly occurrences of tranquilityite were discovered in six places in the Pilbara region in Western Australia . These include some dykes and tunnels made of diabase and gabbro rock that date from the Proterozoic to Cambrian . The tranquilityite occurs here in the form of embedded grains in zirconolite , baddeleyite and apatite , associated with end-phase adhesions of quartz and feldspar .

literature

  • Tranquilityite . In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America . 2001 ( handbookofmineralogy.org [PDF; 65 kB ; accessed on May 23, 2018]).
  • Birger Rasmussen, Ian R. Fletcher, Courtney J. Gregory, Janet R. Muhling, Alexandra A. Suvorova: Tranquilityite: The last lunar mineral comes down to Earth . In: Geology . tape 40 , no. 1 , 2012, p. 83-86 , doi : 10.1130 / G32525.1 .

Web links

Individual evidence

  1. ↑ a b c d Hugo Strunz , Ernest H. Nickel : Strunz Mineralogical Tables. Chemical-structural Mineral Classification System . 9th edition. E. Schweizerbart'sche Verlagbuchhandlung (Nägele and Obermiller), Stuttgart 2001, ISBN 3-510-65188-X , p.  554 .
  2. ↑ a b c J. F. Lovering et al .: Tranquilityite: A new silicate mineral from Apollo 11 and Apollo 12 basaltic rocks . In: Proceedings of the Lunar Science Conference . 2, 1971, pp. 39-45. bibcode : 1971LPSC .... 2 ... 39L .
  3. ↑ a b c d Mindat - Tranquilityite (English)
  4. ↑ a b Rob Waugh: Last unique 'moon mineral' brought back by Apollo astronauts is found in billion-year-old Australian rocks . Daily Mail. Archived from the original on January 7, 2012. Retrieved January 7, 2012.
  5. ^ Paul Ramdohr , Ahmed El Goresy: Opaque Minerals of the Lunar Rocks and Dust from Mare Tranquillitatis . In: Science . tape  167 , no. 3918 , January 30, 1970, p. 615-618 , doi : 10.1126 / science.167.3918.615 , PMID 17781517 .
  6. ^ Eugene N. Cameron: Opaque minerals in certain lunar rocks from Apollo 11 . In: Geochimica et Cosmochimica Acta Supplement . tape 1 , 1970, p. 193-206 , bibcode : 1970GeCAS ... 1..221C (Proceedings of the Apollo 11 Lunar Science Conference held January 5-8, 1970 in Houston, TX).
  7. ↑ MR Dence, JAV Douglas, AG Plant, RJ Traill: Petrology, Mineralogy and Deformation of Apollo 11 Samples . In: Geochimica et Cosmochimica Acta Supplement . tape 1 , 1970, p. 315-340 , bibcode : 1970GeCAS ... 1..315D (Proceedings of the Apollo 11 Lunar Science Conference (January 5-8, 1970, Houston, TX)).
  8. ↑ Charles Meyer: Sample 10047: Ilmenite Basalt (low K) 138 grams Figure (PDF; 505 kB) In: NASA Lunar Sample Compendium . NASA. 2009. Retrieved January 7, 2012.
  9. ↑ The official IMA-CNMNC List of Mineral Names (PDF; 1.9 MB) In: Commission on New Minerals, Nomenclature And Classification . International Mineralogical Association . 2009. Retrieved January 7, 2012.
  10. ^ Grant Heiken, David Vaniman, Bevan M. French: Lunar Sourcebook: a User's Guide to the Moon . Cambridge Univ. Press, Cambridge 1991, ISBN 9780521334440 , pp. 133-134 (accessed January 7, 2012).
  11. ↑ Robert M. Walker, Robert L. Fleischer, P. Buford Price: Nuclear tracks in solids: principles and applications . University of California Press, Berkeley 1975, ISBN 9780520026650 (Retrieved January 7, 2012).
  12. ↑ a b c B. M. Gatehouse, IE Gray, JF Lovering, DA Wark: Structural studies on tranquilityite and related synthetic phases . In: Pergamon Press, Inc. (Ed.): Proceedings of the Lunar Science Conference, 8th, Houston, Tex., March 14-18, 1977 . 2 (A78-41551 18-91), New York, 1977, pp. 1831-1838. bibcode : 1977LPSC .... 8.1831G .
  13. ↑ Birger Rasmussen, Ian R. Fletcher, Janet R. Muhling: Pb / Pb Geochronology, Petrography and Chemistry of Zr-rich Accessory Minerals (Zirconolite, Tranquilityite and Baddeleyite) in Mare Basalt 10047 . In: Geochimica et Cosmochimica Acta . 72, No. 23, 2008, pp. 5799-5818. bibcode : 2008GeCoA..72.5799R . doi : 10.1016 / j.gca.2008.09.010 .
  14. ↑ JR Hinthorne, CA Andersen, RL Conrad, JF Lovering: Single-grain 207Pb / 206Pb and U / Th age determinations with a 10-micron spatial resolution using the ion microprobe mass analyzer (IMMA) . In: Chem. Geology . 25, No. 4, 1979, pp. 271-303. doi : 10.1016 / 0009-2541 (79) 90061-5 .
  15. ↑ Michael Fleischer : New Mineral Names . In: American Mineralogist . tape  58 , no. 1-2 , 1973, pp. 139–141 ( minsocam.org [PDF; 331 kB ; accessed on May 23, 2018]).
  16. ↑ Lunar Sample Mineralogy (PDF; 469 kB) NASA. Retrieved January 13, 2011.
  17. ^ Sara S. Russell, Jutta Zipfel, Jeffrey N. Grossman, Monica M. Grady: The Meteoritical Bulletin N ° 86 2002 July . In: Meteoritics & Planetary Science . 37, 2002, p. A157. doi : 10.1111 / j.1945-5100.2002.tb00913.x .
  18. ^ Hugues Leroux, Patrick Cordier: Magmatic cristobalite and quartz in the NWA 856 Martian meteorite . In: Meteoritics & Planetary Science . 41, No. 6, 2006, pp. 913-923. doi : 10.1111 / j.1945-5100.2006.tb00495.x .
  19. ↑ a b Birger Rasmussen, Ian R. Fletcher, Courtney J. Gregory, Janet R. Muhling, Alexandra A. Suvorova: Tranquilityite: The last lunar mineral comes down to Earth . In: Geology . 40, No. 1, 2012, pp. 83-86. doi : 10.1130 / G32525.1 .
  20. ^ Rare Moon mineral found in Australia. In: www.abc.net.au. Australian Broadcasting Corporation, January 5, 2012, accessed May 23, 2018 .