Kushiroite

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Kushiroite
General and classification
other names
  • Calcium Tschermak's Pyroxen (CaTs)
  • IMA 2008-059
chemical formula
  • CaAlAlSiO 6
  • Ca (Al, Ti 4+ , Mg) [AlSiO 6 ]
Mineral class
(and possibly department) 		Silicates and Germanates
System no. to Strunz
and to Dana 		9.DA.15
65.1.3.8
Crystallographic Data
Crystal system monoclinic
Crystal class ; symbol monoclinic prismatic; 2 / m
Space group C 2 / c (No. 15)Template: room group / 15
Lattice parameters a  = 9.609 (3)  Å ; b  = 8.652 (2) Å; c  = 5.274 (2) Å
α  = 90 °; β  = 106.06 (2) °; γ  = 90 °
Formula units Z  = 4
Physical Properties
Mohs hardness not determined
Density (g / cm 3 ) synthetic: 3.42 (measured) 3.44 (calculated)
Cleavage Please complete!
colour synthetic: colorless / white, natural; colorless
Line color Please complete!
transparency transparent
shine not determined
radioactivity -
magnetism -
Crystal optics
Refractive indices n α  = synthetic: 1.709 (2)
n β  = synthetic: 1.714 (2)
n γ  = synthetic: 1.730 (2)
Birefringence δ = 0.021 (4)

The mineral kushiroite is a very rare chain silicate from the pyroxene group with the idealized chemical composition CaAlAlSiO 6 .

Kushiroite crystallizes with monoclinic symmetry and forms colorless crystals of a few µm in size.

In an early phase of the formation of our solar system, almost pure kushiroite crystallized when calcium-aluminum-rich melt droplets were rapidly cooled in chondritic meteorites . Type locality is the Allan Hills 85085 meteorite (ALH 85085) from the Allan Hills in Victoria Land , East Antarctica, Antarctica , in which kushiroite occurs together with grossite and titanium-rich kushiroite.

Etymology and history

Green Fassait from the Pale Rabbiose (Monti Monzoni, Val di Fassa).

Aluminum-containing pyroxenes have been known as Fassait since the beginning of the 19th century. Initially red-brown zeolites from the Fassa valley were called Fassait , but Abraham Gottlob Werner introduced the name Fassait in 1817 for leek to dark green pyroxenes from the Fassa valley , which are characterized by their well-developed [110] prismatic surfaces.

The characteristic contents of aluminum and ferrous iron (Fe 3+ ) without the corresponding contents of sodium were proven 60 years later by the newly appointed, extraordinary professor for mineralogy and petrography at the University of Graz , Cornelio August Doelter , through the first chemical analyzes of this facade. Doelter emphasized the chemically independent character of Fassaite and subsequently the name Fassait was expanded to include all aluminum and Fe 3+ -containing, low-sodium calcium pyroxenes made from metamorphic sand-lime bricks.

At the same time as Doelter, Gustav Tschermak investigated the compositions of pyroxenes at the University of Vienna and tried to describe them as mixed crystals of a uniform set of end link compositions . In 1913 he documented the coupled exchange reaction 2Al = Mg + Si in aluminum-rich augites , which was later named Tschermak substitution after him , as well as the associated, long-hypothetical, pyroxene end member CaAlAlSiO 6 . This, too, was named after him Calcium-Tschermak-Pyroxen or Calcium-Tschermak-Molecule.

Since the beginning of the 20th century, the maximum levels of trivalent cations of diopside have been explored experimentally. E. R Segnit e.g. B. from the University of Cambridge synthesized diopside with 10% by weight Al 2 O 3 or 8% by weight Fe 2 O 3 in 1953 and J. De Neufville and JF Schairer synthesized diopside calcium Tschermak mixed crystals with a maximum of 20% by weight Calcium-Tschermak-Pyroxen.

At the same time, James Fred Hays determined in 1966 at Harvard University in Cambridge (Massachusetts) and Ken-ichi Hijikata and Kenzo Yagi in 1967 at the University of Hokkaidō in Japan the stability range of the synthetic Calcium-Tschermak-Pyroxene.

Diopsids with ever higher Fe and Al contents have also been found in natural occurrences. In 1956, Knopf & Lee described a facade made of a spinel-containing, metamorphic limestone, in which 0.463 atoms per formula unit (apfu) Si were replaced by Al, and Donald R. Peacor described the structure of a pyroxene from a carbonatite with 0.494 apfu Al on the silicon position in 1967. In 1977 S. Gross documented a Fassaite made of a pyroxen wollastonite - anorthite - rock of the pyrometamorphic Hatrurim formation near Tarqumiya (Palestina) with 0.6 apfu Al on the Si position and 0.41 apfu Fe. 3+ In 1980 Joseph D. Devine and Haraldur Sigurðsson discovered a Fassait with over 40 mol% of the calcium Tschermak pyroxene.

The mineral name Fassait was discredited in 1989 by the Commission on New Minerals and Mineral Names (CNMMN) of the International Mineralogical Association (IMA).

Pyroxenes with even higher contents of the calcium Tschermak molecule have been known since the 1970s from inclusions of the Allende meteorite. B. Steven B. Simon and co-workers published pyroxene analyzes from calcium-aluminum-rich inclusions of various meteorites in 1998 , which showed 20–82 mol% calcium-Tschermak-pyroxene. It took another 11 years until Makoto Kimura and colleagues introduced calcium Tschermak pyroxene as the independent mineral kushiroite in 2009 . They named it after the professor emeritus from Tokyo University Ikuo Kushiro in recognition of his experimental investigations into silicates and calcium Tschermak pyroxene.

classification

In the structural classification of the International Mineralogical Association (IMA) Kushiroit belongs together with pyroxene , Burnettit , Davisit , diopside , Esseneit , Petedunnit , Grossmanit , Hedenbergit , Johannsenite and Tissintit to Kalziumpyroxenen in pyroxene .

The 9th edition of Strunz's mineral systematics, which has been valid since 2001 and has so far been used by the IMA, does not yet list the kushiroite. It would have been assigned to the class of "silicates and germanates" and there in the department of "chain and band silicates (inosilicates)". This section is further subdivided according to the type of chain formation, so that the mineral is classified according to its structure in the sub-section “Chain and band silicates with 2-periodic single chains Si2O6; Pyroxen-Familie "would be to be found, where together with Augite, Diopside, Esseneite, Petedunnit, Hedenbergit and Johannsenite to the" Ca-Klinopyroxene, Diopsidegruppe "with the system no. 9.DA.15 belonged to.

The outdated, but still in use 8th edition of the mineral classification according to Strunz does not know about kushiroite. He would belong to the mineral class of "silicates and Germanates" and then "chain silicates and band silicates (inosilicates)" to the department of where he along with Aegirin , pyroxene, Petedunnit, Esseneit, Hedenbergit, jadeite , Jervisit , Johannsenite, kanoite , clino , Klinoferrosilit , Kosmochlor , Namansilit , Natalyit , Omphacit , Pigeonit and Spodumene the " Pyroxene group, subgroup Klinopyroxene" with the system no. VIII / F.01 .

The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns kushiroite to the class of "silicates and Germanates" and there in the department of "chain silicate minerals". Here it is together with diopside, hedenbergite, augite, johannsenite, petedunnite and davisite in the group of " C 2 / c clinopyroxene (Ca-clinopyroxene)" with system no. 65.01.03.8 within the sub-section " Chain Silicates: Simple unbranched chains, W = 1 with chains P = 2 ".

Chemism

Kushiroite with the idealized composition [M2] Ca [M1] Al 3+ [T] (AlSi) O 6 is the aluminum- aluminum analog of diopside ( [M2] Ca [M1] Mg [T] Si 2 O 6 ), where [M2], [M1] and [T] are the positions in the pyroxene structure.

The compositions of the co-occurring kushiroite and titanium kushiroite are from the type locality

  • [M2] Ca 1.008 [M1] (Al 3+ 0.878 Mg 0.094 Fe 2+ 0.034 ) [T] (Si 1.079 Al 0.921 ) O 6 .
  • [M2] Ca 1.000 [M1] (Al 3+ 0.579 Ti 4+ 0.190 Ti 3+ 0.084 Mg 0.105 Fe 2+ 0.041 ) [T] (Si 0.956 Al 1.044 ) O 6

The incorporation of titanium in kushiroite takes place via two solid solution ranges, corresponding to the exchange reactions

  • [M1] Al 3+ = [M1] Ti 3+ ( Grossmanit )
  • [M1] Al 3+ + [T] Si 4+ = [M1] Ti 4+ + [T] Al 3+ (Al-Buffonite)

Furthermore, kushiroite forms mixed crystals with diopside, agirin and essenite:

  • [M1] Al 3+ + [T] Al 3+ = [M1] Mg 2+ + [T] Si 4+ ( diopside )
  • [M2] Ca 2+ + [M1] Al 3+ + [T] Al 3+ = [M2] Na + + [M1] Fe 3+ + [T] Si 4+ ( Aegirine ).
  • [M1] Al 3+ = [M1] Fe 3+ ( Esseneit )

So far, kushiroite-rich pyroxenes have only been found in meteorites. Terrestrial clinopyroxenes rarely contain more than 20 mol% kushiroite, and the kushiroite contents increase with pressure and temperature.

Crystal structure

Kushiroite crystallizes with monoclinic symmetry in the space group C 2 / c (space group no. 15) with 4 formula units per unit cell . The lattice parameters of the synthetic end  link are a = 9.609 (3) Å, b  = 8.652 (2) Å, c  = 5.274 (2) Å and β = 106.06 (2) °. Structural studies on natural, almost pure kushiroite from various meteorites are also consistent with these values. Template: room group / 15

The structure is that of clinopyroxene . Silicon (Si 4+ ) and aluminum (Al 3+ ) occupy the tetrahedral 4 oxygen ions surrounded T position, calcium (Ca 2+ ) is the octahedrally by 6 oxygens surrounded M2-position and the coordinated also octahedral M1-position is with Aluminum (Al 3+ ) occupied.

Education and Locations

Pure kushiroite is stable at high temperatures and pressures. Below 10 kbar, kuschiroite is mined to anorthite , gehlenite and corundum . At low temperatures or high pressures beyond a line of 1000 ° C / 10 kBar and 1500 ° C / 25 kBar, kushiroite degrades into grossular and corundum and at temperatures above 1400 ° C, kushiroite melts incongruously to melt and corundum. A mixed crystal formation with diopside extends the stability field to lower temperatures and pressures. Incorporation of aegirine stabilizes kushiroite at lower temperatures and higher pressures.

In contrast to these experimental results, almost pure kushiroite was found in calcium-aluminum-rich inclusions (CAI) of carbonaceous chondrites , where it was formed at very low pressures of 0.001 bar (or less), high temperatures and extremely reducing conditions. Some authors therefore assume a metastable formation of kushiroite in the presolar nebula during the early phase of the formation of the solar system .

On the other hand, thermodynamic equilibrium calculations show that kushiroite forms when the presolar nebula cools from ~ 1430 ° C when Melilite reacts with a hot, Si and Mg-containing gas phase. According to these calculations, the anorthite to be expected in accordance with the experimental findings forms together with diopside-rich pyroxene only when the temperature is further cooled to ~ 1370 ° C and the condensation of silicon continues.

Meteorites

Type locality is the Allan Hills 85085 Meteorite (ALH 85085), a carbonaceous chondrite from the Allan Hills in Victoria Land, East Antarctica, Antarctica. Kushiroite was discovered here in CAIs, where it occurs together with grossite and a titanium-rich grossmanite-kushiroite mixed crystal.

In the Allende meteorite , almost pure kushiroite was found in the inner area of ​​a loose ("fluffy") CAI. It occurs here as an inclusion in gehlenite , together with hibonite , perovskite , corundum , grossmanite, spinel , grossular , anorthite and nepheline .

CAIs containing kushiroite were also found in the Murray CM2 meteorite. These are melt droplets that have crystallized into kushiroite and hibonite.

In the carbonaceous chondrite Acfer 214 CH, which was found in 1991 in the desert area of Tanezrouft in the province of Tamanghasset in Algeria , kushiroite also occurs in a melted CAI. Accompanying minerals are hibonite, the newly discovered Ca-Al oxide addibischoffite , perovskite, Ti-rich kushiroite, spinel, melilite, anorthite and small amounts of FeNi metal.

Skarne

The oldest known site of Fassait is the Monti Monzoni in the Fassa Valley , Trentino , Italy , of which chemical analyzes were published as early as 1877. The aluminum content of these façades is ~ 10% by weight Al 2 O 3 and 5-10% by weight Fe 2 O 3 , which corresponds to approx. 15-20 mol% kushiroite.

Diopside solid solution with a comparable proportion of the Ca-Tschermak component (kushiroite) has been described by numerous skarns . The diopside portion of the façade almost always predominates and, depending on the composition of the parent rock, they contain different proportions of essenite. Clinopyroxenes, in which the kushiroite predominates, are very rare in terrestrial rocks.

Relict kushiroite- and Esseneit -dominated clinopyroxenes with diopside contents of sometimes less than 30 mol% and up to 38 mol% have been described from the grossular - wollastonite - endoscarnes of Cornet Hill in the Magureaua Vaţei area near Vaţa Bai in the Apuseni Mountains , Romania Kushiroite. They appear as small inclusions in wollastonite, along with kalsilite .

A clinopyroxene mixed crystal with 45 mol% kushiroite, 37 mol% diopside and 15 mol% esseneit was found in a lime silicate xenolite from the deposits of a pyroclastic flow of the La Soufrière volcano on St. Vincent , Lesser Antilles . Accompanying minerals here are grossular andradite-accentuated garnet (grandite), wollastonite, anorthite and calcite .

Pyrometamorphosis

At the Knapp Ranch in Lewis and Clark County in Montana , Fassaite occurs in a pyrometamorphic calcium silicate rock together with spinel, garnet, Clintonite and traces of biotite and muscovite . The kushiroite content here is 22 mol% with 17 mol% essence.

In the pyrometamorphic Hatrurim formation there is food-rich clinopyroxene with 22 mol% kushiroite near Tarqumiya north of Hebron in the West Bank , Palestinian Territories . Accompanying minerals here are anorthite, wollastonite , gehlenite and, as an inclusion, magnetite .

Similar mineral parageneses are formed in the spoil heaps of coal mining, if they have been pyrometamorphically changed in fires. The pyroxenes formed here are mostly rich in iron and the kushiroite contents can reach 37 mol%.

Web links

Individual evidence

  1. ↑ a b Malcolm Back, William D. Birch, Michel Blondieau and others: The New IMA List of Minerals - A Work in Progress - Updated: November 2018. (PDF; 1753 kB) In: nrmima.nrm.se. IMA / CNMNC, Marco Pasero, November 2018, accessed April 29, 2020 .
  2. ↑ Stefan Weiß: The large Lapis mineral directory. All minerals from A - Z and their properties. Status 03/2018 . 7th, completely revised and supplemented edition. Weise, Munich 2018, ISBN 978-3-921656-83-9 .
  3. ↑ a b c Kushiroite. In: mindat.org. Hudson Institute of Mineralogy, accessed March 27, 2019 .
  4. ↑ a b c d e f Fujio Peter Okamura, Subrata Ghose and Haruo Ohashi: Structure and Chrystal Chemistry of Calcium Tschermak's Pyroxene, CaAlAlSiO 6 . In: American Mineralogist . tape 59 , 1974, pp. 549–557 (English, rruff.info [PDF; 1.1 MB ; accessed on March 27, 2019]).
  5. ↑ a b c d e f g Chi Ma, Steven B. Simon, George R. Rossman, Lawrence Grossman: Calcium Tschermak's pyroxene, CaAlAlSiO 6 , from the Allende and Murray meteorites: EBSD and micro-Raman characterizations . In: American Mineralogist . tape 94 , 2009, p. 1483–1486 (English, rruff.info [PDF; 741 kB ; accessed on March 27, 2019]).
  6. ↑ a b c d e f g James Fred Hays: Stability and properties of the synthetic pyroxene CaAl 2 SiO 6 . In: The American Mineralogist . tape 51 , 1966, pp. 1524–1529 (English, minsocam.org [PDF; 402 kB ; accessed on March 27, 2019]).
  7. ↑ a b c d e f g Makoto Kimura, Takashi Mikouchi, Akio Suzuki, Masaaki Miyahara, Eiji Ohtani and Ahmed El Goresy: Kushiroite, CaAlAlSiO 6 : A new mineral of the pyroxene group from the ALH 85085 CH chondrite, and its genetic significance in refractory inclusions . In: American Mineralogist . tape 94 , 2009, p. 1479–1482 (English, rruff.info [PDF; 503 kB ; accessed on March 27, 2019]).
  8. ↑ Dtr. and Professor Georg August Bertele: Handbook of Minerography of Simple Fossils. For the use of his lectures . Joseph Attenkofer, Landshut 1804, p. 183 ( google books in the google book search).
  9. ↑ a b C. Doelter: VI. Contributions to the mineralogy of the Fassa and Fleimser Thales . In: Mineralogical messages . 1877, p. 65–82 ( forgottenbooks.com [PDF; 34.5 MB ; accessed on November 25, 2018]).
  10. ↑ a b Cornelio August Doelter with the participation of numerous experts: Handbuch der Mineralchemie . Ed .: Cornelio August Doelter. Volume II First Half: Silicates . Springer, Berlin, Heidelberg 1914, p. 558 , doi : 10.1007 / 978-3-642-49866-4 ( google books in the google book search).
  11. ↑ a b CE Tilley and HCG Vincent: Aluminous Pyroxenes in Metamorphosed Limestones . In: Geological Magazine . tape 75 , no. 2 , 1938, p. 81-86 , doi : 10.1017 / S0016756800089317 ( cambridge.org ).
  12. ↑ G. Tschermak: XVIII. About the chemical composition of alumina-containing Augite . In: Tschermaks mineralogical and petrographic communications . tape 32 , 1913, pp. 520-534 , doi : 10.1007 / BF02995374 .
  13. ^ ER Segnit: Some data on synthetic aluminous and other pyroxenes . In: Mineralogical Magazine . tape 30 , 1953, pp. 218–223 (English, rruff.info [PDF; 389 kB ; accessed on March 27, 2019]).
  14. ^ J. De Neufville, JF Schairer: The join diopside-Ca Tschermak's molecule at atmospheric pressure . In: Carnegie Institution Washington Year Book . tape 61 , 1962, pp. 56-69 (English).
  15. ↑ a b Ken-ichi Hijikata, Kenzo Yagi: Phase Relations of Ca-Tschermak's Molecule at High Pressures and Temperatures . In: Journal of the Faculty of Science, Hokkaido University. Series 4, Geology and mineralogy . tape 13 , no. 4 , 1967, p. 407-417 ( eprints.lib.hokudai.ac.jp [PDF; 525 kB ; accessed on December 17, 2018]).
  16. ^ A b Adolph Knopf, Donald E. Lee: Fassaite From Near Helena, Montana . In: American Mineralogist . tape 42 , 1956, pp. 73–77 (English, minsocam.org [PDF; 334 kB ; accessed on March 27, 2019]).
  17. ↑ Donald R. Peacor: Refinement of the crystal structure of a Pyroxene of formula M1 M2 (Si 1.5 Al 0.5 ) O 6 . In: American Mineralogist . tape 52 , 1967, p. 31–41 (English, minsocam.org [PDF; 746 kB ; accessed on March 27, 2019]).
  18. ^ A b S. Gross: The mineralogy of the Hatrurim formation, Israel. In: Geol. Surv. Isr. Bull. Band 70 , 1977, pp. 1–80 ( rruff.info [PDF; 5.7 MB ; accessed on July 29, 2018]).
  19. ^ A b Joseph D. Devine and Haraldur Sigurðsson: Garnet-fassaite calc-silicate nodule from La Soufrière, St. Vincent . In: American Mineralogist . tape 65 , 1980, pp. 302–305 ( minsocam.org [PDF; 457 kB ; accessed on December 28, 2018]).
  20. ↑ Subcommite on Pyroxenes, CNMMN; Nobuo Morimoto: Nomenclature of Pyroxenes . In: The Canadian Mineralogist . tape 27 , 1989, pp. 143–156 ( mineralogicalassociation.ca [PDF; 1.6 MB ; accessed on November 11, 2018]). mineralogicalassociation.ca ( Memento from March 9, 2008 in the Internet Archive )
  21. ^ Roy S. Clarke Jr., Eugene Jarosewich, Brian Mason, Joseph Nelen, Manuel Gomez, Jack R. Hyde: Aluminum-titanium-rich pyroxenes, with special reference to the Allende meteorite . In: Smithsonian Contributions to the Earth Sciences . tape 5 , 1970, p. 1–53 (English, repository.si.edu [PDF; 27.3 MB ; accessed on March 27, 2019]).
  22. ^ Brian Mason: Aluminum-titanium-rich pyroxenes, with special reference to the Allende meteorite . In: American Mineralogist . tape 59 , 1974, pp. 1198–1202 (English, minsocam.org [PDF; 558 kB ; accessed on March 27, 2019]).
  23. ^ A b Steven B. Simon, Andrew M. Davis, Lawrence Grossman, Ernst K. Zinner: Origin of hibonite-pyroxene spherules found in carbonaceous chondrites . In: Meteoritics & Planetary Science . tape 33 , 1998, pp. 411-424 (English, onlinelibrary.wiley.com [PDF; 2.4 MB ; accessed on March 27, 2019]).
  24. ^ Chi Ma, John R. Beckett, and George R. Rossman: Grossmanite, Davisite, and Kushiroite: Three Newly-approved Diopside-Group Clinopyroxenes in CAIs . In: Lunar and Planetary Science Conference . tape 41 , 2010 ( lpi.usra.edu [PDF; 996 kB ; accessed on December 17, 2018]).
  25. ↑ a b Ken-ichi Hijikata: Phase Relations in the System CaMgSi_2O_6-CaAl_2SiO_6 at High Pressures and Temperatures . In: Journal of the Faculty of Science, Hokkaido University. Series 4, Geology and mineralogy . tape 16 (1) , 1973, pp. 167–178 ( eprints.lib.hokudai.ac.jp [PDF; 579 kB ; accessed on December 11, 2018]).
  26. ↑ a b c Kazuo Yoshikawa: Phase relations and the nature of clinopyroxene solid solutions in the system NaFe 3+ Si 2 O 6 - CaMgSi 2 O 6 - CaAl 2 SiO 6 . In: Journal of the Faculty of Science, Hokkaido University. Series 4, Geology and mineralogy . tape 17 , no. 3 , 1977, pp. 451–485 (English, eprints.lib.hokudai.ac.jp [PDF; 1.8 MB ; accessed on March 27, 2019]).
  27. ↑ a b SB Simon, AM Davis, L. Grossman: Formation of orange hibonite, as inferred from some Allende inclusions . In: Meteoritics & Planetary Science . tape 36 , 2001, p. 331-350 , doi : 10.1111 / j.1945-5100.2001.tb01877.x ( onlinelibrary.wiley.com [PDF; 2.2 MB ]).
  28. ^ Lawrence Grossman: Vapor-condensed phase processes in the early solar system . In: Meteoritics & Planetary Science . tape 45 , 2010, p. 7–20 ( onlinelibrary.wiley.com [PDF; 2.0 MB ; accessed on December 23, 2018]).
  29. ↑ Chi Ma, Alexander N. Krot, Kazuhide Nagashima: Addibischoffite, Ca2Al6Al6O20, a new calcium aluminate mineral from the Acfer 214 CH carbonaceous chondrite: A new refractory phase from the solar nebula . In: American Mineralogist . tape 102 , 2017, p. 1556–1560 ( minsocam.org [PDF; 1.6 MB ; accessed on December 17, 2018]).
  30. ↑ Marie-Lola Pascal, Ildiko Katona, Michel Fonteilles, Jean Verkaeren: RELICS OF HIGH-TEMPERATURE CLINOPYROXENE ON THE JOIN Di – CaTs WITH UP TO 72 mol.% Ca (Al, Fe3 +) AlSiO6 IN THE SKARNS OF CICLOVA AND MAGUREAUA VATEI, CARPATHIANS, ROMANIA . In: The Canadian Mineralogist . tape 43 , 2005, p. 857881 ( rruff.info [PDF; 1.6 MB ; accessed on December 28, 2018]).
  31. ↑ Justyna Ciesielczuk, Łukasz Kruszewski, Jarosław Majka: Comparative mineralogical study of thermally-altered coal-dump waste, natural rocks and the products of laboratory heating experiments . In: International Journal of Coal Geology . tape 139 , 2015, p. 114–141 ( s3.amazonaws.com [PDF; 4.8 MB ; accessed on December 4, 2018]).