TY - JOUR
T1 - Discovery of terrestrial rubinite, Ca3Ti3+2Si3O12, super-reduced garnet from the Hatrurim Complex, Israel
AU - Galuskin, Evgeny V.
AU - Galuskina, Irina O.
AU - Kusz, Joachim
AU - Vapnik, Yevgeny
AU - Zieliński, Grzegorz
N1 - Publisher Copyright:
© The Author(s), 2025. Published by Cambridge University Press on behalf of The Mineralogical Society of the United Kingdom and Ireland.
PY - 2025/1/1
Y1 - 2025/1/1
N2 - Rubinite, a garnet with the ideal formula Ca3Ti3+2Si3O12, is an indicator of super-reduced conditions and has recently been found in refractory inclusions in a few CV3 chondrites. We discovered rubinite in phosphide-bearing breccia from the pyrometamorphic Hatrurim Complex, Negev Desert, Israel. Aggregates of phosphide and native iron are concentrated at the boundary of thermally altered sedimentary xenoliths encased in flamite-gehlenite paralava. Rubinite, with the average empirical formula (Ca2.97Mg0.02Fe2+0.01)∑3.00 (Ti3+1.10 Al0.44Ti4+0.37Mg0.08Cr0.01)∑2(Si2.71Al0.29)∑3.00O12, was found in a small xenolith composed of hydrogrossular, tacharanite and calcite, and containing relics of high-temperature minerals such as pseudowollastonite, cuspidine, gehlenite, baghdadite, barringerite, murashkoite, osbornite, paqueite and oldhamite. For the first time, a structure of rubinite, with the composition (Ca2.99Mg0.01)∑3(Ti3+0.78Al0.62 Ti4+0.43Mg0.17)∑2(Si2.74 Al0.26)∑3O12, has been refined. Its unit-cell parameter a = 12.0193(4)Å, is significantly smaller than that of the synthetic analogue of Ca3Ti2Si3O12, 12.1875Å. In a Raman spectrum of rubinite weak bands corresponding to the vibrations of Ti4+-O in the (TiO6)8- octahedra: 610 cm-1 ν1(TiO6)8- and 438 cm-1 ν4(TiO6)8- are present in addition to the bands related to Si-O and Al-O vibrations in the TO4 tetrahedra. Rubinite forms a thin reactive rim (<10 μm) on pseudowollastonite grains. It likely formed during a sharp increase in rock porosity in the course of natural clinkerisation of sedimentary xenoliths caused by the thermal impact of the paralava. The high porosity increased the effect of reductive gases on the rocks, which were by-products of pyrometamorphism. The brief appearance of super-reduced conditions defined the formation of the Ti3+-bearing minerals osbornite and rubinite.
AB - Rubinite, a garnet with the ideal formula Ca3Ti3+2Si3O12, is an indicator of super-reduced conditions and has recently been found in refractory inclusions in a few CV3 chondrites. We discovered rubinite in phosphide-bearing breccia from the pyrometamorphic Hatrurim Complex, Negev Desert, Israel. Aggregates of phosphide and native iron are concentrated at the boundary of thermally altered sedimentary xenoliths encased in flamite-gehlenite paralava. Rubinite, with the average empirical formula (Ca2.97Mg0.02Fe2+0.01)∑3.00 (Ti3+1.10 Al0.44Ti4+0.37Mg0.08Cr0.01)∑2(Si2.71Al0.29)∑3.00O12, was found in a small xenolith composed of hydrogrossular, tacharanite and calcite, and containing relics of high-temperature minerals such as pseudowollastonite, cuspidine, gehlenite, baghdadite, barringerite, murashkoite, osbornite, paqueite and oldhamite. For the first time, a structure of rubinite, with the composition (Ca2.99Mg0.01)∑3(Ti3+0.78Al0.62 Ti4+0.43Mg0.17)∑2(Si2.74 Al0.26)∑3O12, has been refined. Its unit-cell parameter a = 12.0193(4)Å, is significantly smaller than that of the synthetic analogue of Ca3Ti2Si3O12, 12.1875Å. In a Raman spectrum of rubinite weak bands corresponding to the vibrations of Ti4+-O in the (TiO6)8- octahedra: 610 cm-1 ν1(TiO6)8- and 438 cm-1 ν4(TiO6)8- are present in addition to the bands related to Si-O and Al-O vibrations in the TO4 tetrahedra. Rubinite forms a thin reactive rim (<10 μm) on pseudowollastonite grains. It likely formed during a sharp increase in rock porosity in the course of natural clinkerisation of sedimentary xenoliths caused by the thermal impact of the paralava. The high porosity increased the effect of reductive gases on the rocks, which were by-products of pyrometamorphism. The brief appearance of super-reduced conditions defined the formation of the Ti3+-bearing minerals osbornite and rubinite.
KW - garnet
KW - Hatrurim Complex
KW - Israel
KW - paralava
KW - Raman
KW - rubinite
KW - structure
KW - super-reduced minerals
KW - terrestrial rock
UR - http://www.scopus.com/inward/record.url?scp=85216191617&partnerID=8YFLogxK
U2 - 10.1180/mgm.2025.3
DO - 10.1180/mgm.2025.3
M3 - Article
AN - SCOPUS:85216191617
SN - 0026-461X
JO - Mineralogical Magazine
JF - Mineralogical Magazine
ER -