Megawite, CaSnO3: a new perovskite-group mineral from skarns of the Upper Chegem caldera, Kabardino-Balkaria, Northern Caucasus, Russia
| Autor: | A. G. Gurbanov, Piotr Dzierżanowski, Krystian Prusik, Nikolai N. Pertsev, V. M. Gazeev, Aleksandr E. Zadov, Irina O. Galuskina, E. V. Galuskin, Radu Bailau |
|---|---|
| Rok vydání: | 2011 |
| Předmět: |
Mineral
010504 meteorology & atmospheric sciences Brucite Hydrogrossular Geochemistry Metamorphism Mineralogy Skarn engineering.material 010502 geochemistry & geophysics 01 natural sciences Geochemistry and Petrology engineering Afwillite Spurrite Geology 0105 earth and related environmental sciences Perovskite (structure) |
| Zdroj: | Mineralogical Magazine. 75:2563-2572 |
| ISSN: | 1471-8022 0026-461X |
| DOI: | 10.1180/minmag.2011.075.5.2563 |
| Popis: | Megawite is a perovskite-group mineral with an ideal formula CaSnO3 that was discovered in altered silicate-carbonate xenoliths in the Upper Chegem caldera, Kabardino-Balkaria, Northern Caucasus. Russia. Megawite occurs in ignimbrite, where it forms by contact metamorphism at a temperature >800°C and low pressure. The name megawite honours the British crystallographer Helen Dick Megaw (1907—2002) who did pioneering research on perovskite-group minerals. Megawite is associated with spurrite, reinhardbraunsite, rondorfite, wadalite, srebrodolskite, lakargiite, perovskite, kerimasite. elbrusite-(Zr), periclase, hydroxylellestadite, hydrogrossular, ettringite-group minerals, afwillite. hydrocalumite and brucite. Megawite forms pale yellow or colourless crystals up to 15 urn on edge with pseudo-cubic and pseudo-cuboctahedral habits. The calculated density and average refractive index are 5.06 g cm–3 and 1.89, respectively. Megawite is Zr-rich and usually crystallizes on lakargiite. CaZrO3. The main bands in the Raman spectrum of megawite are at: 159, 183, 262, 283, 355, 443. 474, 557 and 705 cm–1. The unit-cell parameters and space group of megawite, derived from electron back scattered diffraction, are: a = 5.555(3), b = 5.708(2), c = 7.939(5) Å, V = 251.8(1) Å3, Pbnm, Z = 4; they are based on an orthorhombic structural model for the synthetic perovskite CaSn0.6Zr0.4O3. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|