Burnettite

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Burnettite
General and classification
other names

Vanadium-Fassait, V-Fassait, IMA 2013-054

chemical formula CaVAlSiO 6
Mineral class
(and possibly department) 		Silicates and Germanates
System no. according to Strunz 9.DA.15
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  = synthetic: 9.80  Å ; b  = synthetic: 8.85 Å; c  = synthetic: 5.36 Å
α  = 90 °; β  = synthetic: 105.62 °°; γ  = 90 °
Formula units Z  = 4
Physical Properties
Mohs hardness not determined
Density (g / cm 3 ) not determined
Cleavage not determined
Break ; Tenacity not determined
colour green
Line color not determined
transparency not determined
shine not determined
radioactivity -
magnetism -
Crystal optics
Refractive index n  = not determined
Birefringence δ = not determined
Optical character not determined
Axis angle 2V = not determined

The mineral burnettite is an extremely rare chain silicate from the pyroxene group with the idealized chemical composition CaVAlSiO 6 .

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

So far (2019) burnettite has only been detected in the Allende meteorite , where it occurs as an inclusion in the melilite of the calcium-aluminum-rich inclusion (CAI) A-WP1. It is one of the first minerals to crystallize out of the presolar nebula when the solar system was formed .

Etymology and history

As early as 1984, vanadium -rich calcium pyroxenes were described in the Allende meteorites by mineralogists at the California Institute of Technology in Pasadena , USA . There followed discoveries vanadium-rich Fassaite which are Kushiroit - Grossmanit - Davisit - diopside - mixed crystals , in Leoville chondrite (1992), the CAI of Efremovka meteorites (2002), in the Ningqiang carbonaceous chondrite (2003) and in the Murchison carbonaceous CM2 chondrite, before Chi Ma and John R. Beckett described calcium vanadium clinopyroxene as a new mineral in 2013. They named it burnettite in honor of cosmochemist Donald S. Burnett of the California Institute of Technology in Pasadena.

Various synthetic vanadium pyroxenes, including the synthetic equivalent of burnettite, were prepared and spectroscopically investigated as early as 2012 .

classification

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

Even the outdated, but still in use 8th edition of the mineral classification according to Strunz does not know the burnettite. 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 , would place Burnettite in the class of "silicates and Germanates" and there in the department of "chain silicate minerals". Here it would be together with diopside, davisite, hedenbergite, augite, johannsenite, petedunnite and kushiroite in the group of " C 2 / c clinopyroxene (Ca-clinopyroxene)" with the system no. 65.01.03.7 can be found in the subsection " Chain Silicates: Simple unbranched chains, W = 1 with chains P = 2 ".

Chemism

Burnettite with the idealized composition [M2] Ca [M1] V 3+ [T] (AlSi) O 6 is the vanadium (V) analog of kushiroite ( [M2] Ca [M1] Al [T] (AlSi) O 6) ), Essenite ( [M2] Ca [M1] Fe 3+ [T] (AlSi) O 6 ) and Davisite ( [M2] Ca [M1] Sc 3+ [T] (AlSi) O 6 ), where [M2] , [M1] and [T] are the positions in the pyroxene structure.

Next to natalyite, burnettite is the second vanadium pyroxene.

The composition of the burnettite from the type locality is

  • [M2] Ca 1.04 [M1] (V 3+ 0.29 Sc 3+ 0.24 Ti 3+ 0.13 Ti 4+ 0.12 Al 0.09 Mg 0.08 ) [T] (Si 1 , 01 Al 0.99 ) O 6 .

There is presumably complete miscibility of burnettite with davisite, grossmanite and kushiroite according to the exchange reactions

  • [M1] V 3+ = [M1] Sc 3+ (Davisite)
  • [M1] V 3+ = [M1] Ti 3+ (Grossmanit)
  • [M1] V 3+ = [M1] Al 3+ (kushiroite)

The magnesium contents go back to a mixed crystal formation with diopside ,

  • [M1] V 3+ + [T] Al 3+ = [M1] Mg 2+ + [T] Si 4+ (diopside)

and tetravalent titanium (Ti 4+ ) can via the coupled substitution

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

to be built in.

Crystal structure

Burnettite 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 natural mixed crystal are a  = 9.80  Å , b  = 8.85 Å, c  = 5.36 Å and β = 105.62 °. Template: room group / 15

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

Education and Locations

Burnettite has so far only been found in meteorites, where it occurs in calcium-aluminum-rich inclusions (CAI), which are rich in high-melting oxides of scandium , vanadium , zirconium and titanium . Vanadium-rich pyroxenes were found as crusts around so-called foreign bodies , mostly tiny aggregates of vanadium-rich magnetite , scheelite , molybdenite , apatite and granules of platinum metals . These foreign bodies formed under oxidizing conditions existed before the formation of the calcium-aluminum-rich inclusions, in which they themselves were enclosed and from which they were partially resorbed under extremely reducing conditions . The vanadium released in the process was incorporated into scandium-titanium-vanadium-rich pyroxenes.

Another way burnettite occurs is small inclusions of isolated crystals in melilite . For them, both a formation as an early condensate from the cooling presolar mist (before Melilith), as well as the formation as a residue from partial melting and distillation of more volatile elements during heating of a CAI is discussed.

The type locality is the Allende meteorite , a carbonaceous chondrite that fell on February 8, 1969 near Parral in Chihuahua in Mexico . Burnettite was discovered here in CAI A-WP1, where it occurs in the form of crystals a few µm in size as an isolated inclusion in Melilite. Strangers with vanadium-rich pyroxenes in contact with the minerals of the CAI were also found in the Allende meteorite.

In Murchison CM2 chondrite vanadium-rich Davisit in the CAI "MURI" was found where he along with Thortveitit , panguite and spinel occurs.

In the CAI 101.1 from the Efremovka meteorite, a carbonaceous chondrite of type CV3, vanadium-rich davisite occurs as an encrustation of perovskite , together with spinel and gehlenite- rich melilite, in which there are inclusions of metallic NiFe. The history of these inclusions is complex, beginning with the early condensation of Sc, - Zr and rare earth-rich Ca-Al compounds, remelting and aggregation of various inclusions and subsequent oxidation .

Burnettite is found as an isolated inclusion in gehlenite in the CAI NQW1–20 of the carbonaceous chondrite Ningqiang.

Titanium- and vanadium-rich davisite has also been described in CAI "R3C-01-U1" of the RBT-04143 chondrite from the Roberts massif in Antarctica. These are also isolated inclusions of very small crystals in gehlenite.

Web links

Individual evidence

  1. ↑ a b c d e f g Chi Ma: Burnettite, IMA2013-054. CNMNC Newsletter No. 17 . In: Mineralogical Magazine . tape 77 , 2013, p. 3002 ( degruyter.com [PDF; 120 kB ; accessed on February 20, 2019]).
  2. ^ Burnettite in: IMA Database of Mineral Properties
  3. ↑ a b Burnettite at mindat.org
  4. ↑ a b c d e f g h i j Chi Ma and John R. Beckett: BURNETTITE, CaVAlSiO6, AND PAQUEITE, Ca3TiSi2 (Al2Ti) O14, TWO NEW MINERALS FROM ALLENDE: CLUES TO THE EVOLUTION OF A V-RICH Ca-Al -RICH INCLUSION. In: Lunar and Planetary Science . tape 47 , 2016, p. 1595-1595 ( usra.edu [PDF; 963 kB ; accessed on February 19, 2019]).
  5. ^ A b CLV Caillet & PR Buseck: The "White Angel": A Wollastonite-Bearing Refractory Inclusion in the Leoville Chondrite . In: Meteoritics . tape 27 , 1992, pp. 208 , bibcode : 1992Metic..27R.208C .
  6. ^ A b c JT Armstrong, A. El Goresy, GP Meeker & GJ Wasserburg: Willy: a Prize Noble Fremdling . In: Lunar and Planetary Science . tape 15 , 1984, pp. 13-14 , bibcode : 1984LPI .... 15 ... 13A .
  7. ^ A b c A. El Goresy, JT Armstrong & GJ Wasserburg: Allende 5241: Anatomy of a Fremdlinge-Rich CAI . In: Lunar and Planetary Science . tape 15 , 1984, pp. 242-243 , bibcode : 1984lpi .... 15..242e .
  8. ↑ a b A. EL GORESY, E. ZINNER, S. MATSUNAMI, H. PALME, B. SPETTEL, Y. LIN and M. NAZAROV: Efremovka 101.1: A CAI with ultrarefractory REE patterns and enormous enrichments of Sc, Zr, and Y in Fassaite and Perovskite . In: Geochimica et Cosmochimica Acta . tape 66 (8) , 2002, pp. 1459-1491 ( semanticscholar.org [PDF; 1.6 MB ; accessed on February 13, 2019]).
  9. ↑ a b c Yangting LIN, Makoto KIMURA and Daode WANG: Fassaites in compact type A Ca-Al-rich inclusions in the Ningqiang carbonaceous chondrite: Evidence for partial melting in the nebula . In: Meteoritics & Planetary Science . tape 38 (3) , 2003, p. 407-417 ( wiley.com [PDF; 6.5 MB ; accessed on February 13, 2019]).
  10. ↑ a b Chi Ma, John R. Beckett, Oliver Tschauner and George R. Rossman: THORTVEITITE (Sc2Si2O7), THE FIRST SOLAR SILICATE? In: Meteoritics and Planetary Science . 46 (S1), 2011, pp. A144 ( caltech.edu [PDF; 96 kB ; accessed on February 20, 2019]).
  11. ↑ Michail N. Taran, Haruo Ohashi: Optical absorption spectroscopy study of three synthetic V3 + -bearing clinopyroxenes . In: European Journal of Mineralogy . tape 24 (5) , 2012, pp. 823-829 , doi : 10.1127 / 0935-1221 / 2012 / 0024-2220 .
  12. ↑ Find location list for burnettite at the Mineralienatlas and at Mindat
  13. ↑ a b Takashi Yoshizaki, Daisuke Nakashima, Tomoki Nakamura, Changkun Park, Naoya Sakamoto, Hatsumi Ishida, Shoichi Itoh: Nebular history of an ultrarefractory phase bearing CAI from a reduced type CV chondrite (preprint) . In: arXiv.org . 2018 ( arxiv.org [PDF; 10.1 MB ; accessed on February 19, 2019]).