Kruszewski, Ł; Gatel, P; Thiéry, V; Moszumańska, I; Kusy, D
Mineralogy and crystal chemistry of minerals constituting slags of the burnt Lapanouse-de-Sévérac oil-shale gobs were examined in detail. The minerals and groups characterized include anhydrite, apatite group, calcium ferrites, cancrinite group (giuseppettite and two depmeierite-like species with latiumite and tuscanite members involved), clinopyroxene subgroup, cuspidine, ettringite group, garnet group, hematite, larnite, leucite, melilite group, nepheline, oldhamite, olivine group, perovskite, petalite-like species, plagioclase, pseudobrookite, pyrrhotite, spinel group, titanite, vaterite, wollastonite, ye'elimite, and numerous associating, accessory minerals. At least 16 potentially new mineral species were found: V-analogue of fluorapatite; Ca–Al phosphate silicate fluoride; “magnesiograndiferrite” amphibole-like phases A, B, and C; dominant ferri-gehlenite; Ca(Na) titanate(niobate); “Ba-petalite” and “K-petalite” Mg–Ti-[] analogue of batiferrite; pyrrhotite-like Fe10S9 phase; and two Zn-bearing Fe3+-Cr and Fe3+ oxides, “ferro-ferri-shulamitite” and a supposed Ca pyrosulfate/disilicate. Most of the compounds analyzed have anomalous and far-from-ideal compositions suggestive for large-bias formation conditions. Formation of untypical solid solutions and small to moderate parts of many hypothetical end-members are suggested to best describe the crystals chemistry. The slags may have formed in the mean 1150–1250°C thermal range.