Mineralogy of pyrometamorphic rocks associated with naturally burned coal-bearing spoil-heaps of the Chelyabinsk coal basin, Russia
Sokol, Ella; Volkova, Nina; Lepezin, Gennady
European Journal of Mineralogy Volume 10 Number 5 (1998), p. 1003 - 1014
published: Oct 5, 1998
manuscript accepted: Mar 26, 1998
manuscript received: Feb 14, 1997
ArtNo. ESP147051005013, Price: 29.00 €
Abstract Pyrometamorphic rocks generated during spontaneous burning of spoil-heaps in the Chelyabinsk coal basin, South Urals, contain a variety of high-temperature minerals, some with diverse and unusual compositons. Optical microscopy, X-ray diffraction, X-ray fluorescence, and microprobe analyses were performed to study the mineralogy of annealed and fused waste rocks. A wide spectrum of rare minerals was found, including tridymite, crystobalite, mullite, K-bearing cordierite, K-Mg-osumilite, and Fe3+,Al-rich Caclinopyroxene, as well as hexagonal and orthorhombic analogues of anorthite. It is suggested that the mineralogy of pyrometamorphic rocks is mainly governed by bulk chemical composition, annealing temperature, and oxygen fugacity; moreover, varying degrees of disequilibrium melting, mixing, crystallization, volatilization and a variety of reaction mechanisms influence the formation, structure and chemistry of the constituent minerals.