Rubinite

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Rubinite
General and classification
other names

IMA 2016-110

chemical formula Ca 3 Ti 3+ 2 Si 3 O 12
Mineral class
(and possibly department) 		Silicates and Germanates
Crystallographic Data
Crystal system cubic
Crystal class ; symbol cubic hexakisoctahedral; 4 / m  3  2 / m
Space group Ia 3 d (No. 230)Template: room group / 230
Lattice parameters a  = synthetic: 12.1875  Å
Formula units Z  = 8
Physical Properties
Mohs hardness not determined
Density (g / cm 3 ) calculated: 3.611
Cleavage not observed
Break ; Tenacity not observed
colour not observed
Line color not observed
transparency not observed
shine not observed
Crystal optics
Refractive index n  = not determined
Birefringence isotropic

The mineral rubinite is a rare island silicate from the upper group of garnets with the idealized chemical composition Ca 3 Ti 3+ 2 Si 3 O 12 . It crystallizes in the cubic crystal system with the structure of garnet.

Rubinite occurs in the form of round grains a few µm in size in calcium-aluminum-rich inclusions (CAI) in carbonaceous chondrites of type CV3. Its type localities are the meteorites Allende and Vigarano . Rubinite is one of the first minerals to be formed when the presolar nebula cooled down at the beginning of the formation of our solar system .

Etymology and history

The compound Ca 3 Ti 3+ 2 Si 3 O 12 was synthesized in 2011 by Martin Valldor André Uthe and Reinhard Rückamp at the University of Cologne .

High-melting residues from the early days of our solar system in CAIs of several CV3 chondrites , including the Vingarano meteorite, were examined by Chi Ma's group at the California Institute of Technology in Pasadena , USA. They were able in 2012 scandium - Garnet Eringait a significant proportion of trivalent titanium (Ti 3+ ) demonstrate. Five years later they succeeded in characterizing a garnet in the same meteorite, which mainly consists of the Ti 3+ component. They named this new mineral of the garnet group rubinite after Alan E. Rubin, a cosmochemist at the University of California , in recognition of his numerous contributions to the study of meteorites.

classification

The structural classification of the International Mineralogical Association (IMA) is one of the Rubinit to Garnet supergroup, where he together with Menzerit- (Y) , pyrope , Grossular , Spessartin , almandine , Goldmanit , Momoiit , Knorringit , Uwarowit , Andradite , Calderit , Eringait , Majorite and morimotoite form the garnet group with 12 positive charges on the tetrahedrally coordinated lattice position.

The 8th edition of the mineral classification according to Strunz , which has been obsolete since 1977 , does not list rubinite. He would, together with almandine, Andradite, Calderit, Goldmanit, Grossular, Eringait, Henritermierit , Hibschite , Holtstamit , Hydrougrandit , katoite , Kimzeyit , Knorringit, majorite, Morimotoit, pyrope, Schorlomit, Spessartin, Uwarowit, wadalite and Yamatoit discredited (because identical with Momoiit ) to the "garnet group" with the system no. VIII / A.08 within the department of the " island silicates include (nesosilicates)".

The 9th edition of Strunz's mineral systematics, which has been valid since 2001 and was last updated by the International Mineralogical Association (IMA) in 2009 , does not yet list rubinite either. Here, however, it would also be classified under the category of "island silicates (nesosilicates)". This is further subdivided here according to the possible presence of further anions as well as the coordination of the cations involved , so that the mineral is classified according to its composition and structure in the subdivision of “island silicates without additional anions; Would cations published in octahedral [6] and to find usually greater coordination, "where it along with almandine, Andradite, Calderit, Goldmanit, Henritermierit , Holtstamit , katoite , Kimzeyit , Knorringit, majorite, Morimotoit, pyrope, Schorlomit , Spessartin and Uwarowit to the "garnet group" with the system no. 9.AD.25 would be counted. The garnet compounds blythite, hibschite, hydroandradite and skiagite, which are no longer regarded as minerals, were also included in this group. Wadalite , at that time still grouped with the grenades, proved to be structurally different and is now assigned to a separate group with chloromayenite and fluoromayenite . The garnets irinarassite , hutcheonite , kerimasite , toturite , eringaite and menzerite- (Y) described after 2001 would have been sorted into the garnet group.

The systematics of minerals according to Dana , which is mainly used in the English-speaking world , would also place rubinite in the class of "silicates and Germanates" and there in the department of "island silicate minerals ". Here it would be together with andradite, goldmanite, uwarovite and yamatoite in the "garnet group (Ugrandite series)" with the system no. 51.04.03b within the subsection “ Island silicates: SiO4 groups only with cations in [6] and> [6] coordination ”.

Chemism

Rubinite is the titanium (Ti 3+ ) analog of Grossular and forms complex mixed crystals mainly with Eringaite , Hutcheonite , Kimzeyite and the Mg analog of Morimotoite . The measured composition from the type locality Allende is

  • [X] (Ca 2.94 Na 0.08 ) [Y] (Ti 3+ 1.05 Ti 4+ 0.66 Mg 0.12 Sc 3+ 0.13 V 3+ 0.04 Fe 2+ 0, 04 Zr 4+ 0.04 ) [Z] (Si 2.38 Al 0.38 Ti 4+ 0.24 ) O 30

and can be regarded as a mixed crystal of rubinite (52 mol%) with 19 mol% hutcheonite, 12 mol% Mg morimotoite and 6 mol% eringaite.

The "rubinite" from the second type locality, the Vigarano meteorite, contains less titanium, is rich in yttrium (Y 3+ ) and zirconium (Zr 4+ ) and has the same composition

  • [X] (Ca 1.98 Y 3+ 0.83 Mg 0.28 ) [Y] (Ti 3+ 0.59 Sc 3+ 0.50 Zr 4+ 0.72 Mg 0.20 V 3+ 0, 02 Cr 3+ 0.01 ) [Z] (Si 1.64 Al 1.18 Ti 4+ 0.07 Fe 2+ 0.06 ) O 30 .

This corresponds to a Kimzeyite (36 mol%) with around 30 mol% rubinite and 15 mol% of a hypothetical yttrium- scandium - aluminum garnet.

Crystal structure

Rubinite crystallizes with cubic symmetry in the space group Ia 3 d (space group no. 230) with 8 formula units per unit cell . The synthetic end  link has the lattice parameter a = 12.1875  Å . Template: room group / 230

The crystal structure is that of garnet . Calcium (Ca 2+ ) occupies the dodecahedral X positions surrounded by 8 oxygen ions, titanium (Ti 3+ ) the octahedral Y position surrounded by 6 oxygen ions and the tetrahedral Z position surrounded by 4 oxygen ions is completely with silicon (Si 4+ ) occupied.

Education and Locations

Like eringaite, rubinite is one of the first solid materials in the presolar nebula . It was formed at very high temperatures and extremely low oxygen fugacities by resublimation or crystallized from a calcium, titanium and aluminum-rich melt.

So far (2020) rubinite has only been found in calcium-aluminum-rich inclusions (CAIs) of CV3 chondrites .

In Vigarano meteorite Rubinit occurs together with Zr panguite , spinel and Davisit -rich diopside in amoeboid Olivinaggregaten on.

In the Allende meteorite Rubinit in flaky (was fluffy ) Type A CAI AE01-01 found. He appears here with gehlenite , perovskite , spinel, Hibonit , corundum , Davisit, Grossmanit and Eringait on. Anorthite , grossular and Na- Melilite are also found as secondary formation .

In the Efremovka meteorite discovered in 1962 near the state farm of the same name near Pavlodarin Kazakhstan, rubinite was found in the compact type A CAIs E101, E105 and 40E-1. Here it occurs with perovskite, spinel and grossmanite as inclusions in gehlenite.

See also

Web links

Individual evidence

  1. ↑ a b C. Ma, T. Yoshizaki, T. Nakamura, J. Muto: Rubinite, IMA 2016-110 . In: CNMNC Newsletter . tape 36 , 2017, p. 343 ( rruff.info [PDF; 505 kB ; accessed on June 6, 2020]).
  2. ↑ a b c d e f g h i j k l m n o p q r Chi Ma, Takashi Yoshizaki, Alexander N. Krot, John R. Beckett, Tomoki Nakamura, Kazuhide Nagashima, Jun Muto, Marina A. Ivanova: Discovery of Rubinite, Ca 3 Ti 3+ 2 Si 3 O 12 , a New Garnet Mineral in Refractory Inclusions from Carbonaceous Chondrites . In: 80th Annual Meeting of the Meteoritical Society . 2017 ( hou.usra.edu [PDF; 146 kB ; accessed on June 6, 2020]).
  3. ↑ a b c d Martin Valldor, André Uthe, Reinhard Rückamp: Antiferromagnetic Ground State of Quantum Spins in the Synthetic Imanite, Ca 3 Ti 2 Si 3 O 12 : The Lost Child of the Garnet Family . In: Inorganic Chemistry . tape 50 , no. 20 , 2011, p. 10107-10112 , doi : 10.1021 / ic201057h .
  4. ↑ Chi Ma: Discovery of meteoritic Eringaite, Ca 3 (Sc, Y, Ti) 2 Si 3 O 12 , the first solar garnet? In: 75th Annual Meteoritical Society Meeting (2012) . 2012 ( lpi.usra.edu [PDF; 70 kB ; accessed on June 6, 2020]).
  5. ^ A b Edward S. Grew, Andrew J. Locock, Stuart J. Mills, Irina O. Galuskina, Evgeny V. Galuskin, Ulf Hålenius: IMA Report - Nomenclature of the garnet supergroup . In: American Mineralogist . tape 98 , 2013, p. 785-811 ( cnmnc.main.jp [PDF; 2.0 MB ; accessed on June 6, 2020]).
  6. ↑ Ernest H. Nickel , Monte C. Nichols: IMA / CNMNC List of Minerals 2009. (PDF; 1.82 MB) In: cnmnc.main.jp. IMA / CNMNC, January 2009, accessed June 6, 2020 .
  7. ↑ List of locations for rubinite in the Mineralienatlas and Mindat , accessed on June 6, 2020.
  8. ↑ Efremovka. In: lpi.usra.edu. Meteoritical Bulletin Database, accessed June 6, 2020 .
  9. ↑ Efremovka meteorite, Pavlodar, Pavlodar Region, Kazakhstan. In: mindat.org. Hudson Institute of Mineralogy, accessed June 6, 2020 .