Earth and Planetary Science

Discovery of the Naturally Occurring Pure CaTiO3 Cubic Perovskite from Tazheran Massif

Jing Sun

China University of Petroleum, Beijing

Jin Liu

Center for High Pressure Science and Technology Advanced Research, Beijing 102249, China

Fuyang Liu

Center for High Pressure Science and Technology Advanced Research, Beijing 102249, China

Eugene Sklyarov

Institute of the Earth's Crust, Siberian Branch of the Russian Academy of Sciences, Irkutsk 664033, Russia

Ross Mitchell

Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, 100029, China

DOI: https://doi.org/10.36956/eps.v3i1.991

Received: 23 November 2023; Published: 25 April 2024

Abstract

As the parent compound of the perovskite-structured family and an analogue of davemaoite CaSiO3 in Earth’s lower mantle, CaTiO3 perovskite is widely used in electronic ceramic materials, immobilizing radioactive waste, and geosciences. Here we report the discovery of a natural pure CaTiO3 perovskite-C in calc-silicate veins in brucite marble in the Tazheran Massif, Russia. The mean composition of perovskite-C is 97 wt% total CaO and TiO2, and minor impurities of Na, Al, and Zr, yielding the chemical formula CaTi0.97Al0.01Na0.01Zr0.01O3. The cubic crystal structure—Pmm, Z = 1: a = 3.8301 Å, V = 56.19 (2) Å3 (ρ = 4.019 g/cm3) has been refined to R1 = 0.0451. Compared with the cubic perovskite discovered in Israel, the cubic perovskite discovered in this study is very pure in Ca and Ti. The naturally occurring perovskite-C from Tazheran implies that the host skarn might have experienced high-temperature (> 1247–1374 °C) metamorphism and/or metasomatism at an early stage. Moreover, the discovery of natural perovskite-C also draws attention to considering crystal-structure-related matrix effects in the future of in situ U-Pb geochronology, especially using Tazh international perovskite standards.

Keywords: Perovskite, Cubic crystal structure, CaTiO3, SCXRD, Tazheran Massif

References