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Secondary sulphate minerals from Bhanine Valley coals (South Lebanon) : a crystallochemical and geochemical study

Kruszewski Łukasz

Geological Quarterly

2019

Vol. 63, No. 1

65--87

Rich efflorescences of various Fe and Al sulphate mineral mixtures on coal seams of Bhanine, South Lebanon, were examined using (1) Powder X-Ray Diffraction (with the Rietveld method and unit cell parameters calculation), (2) Scanning Electron Microscopy with standardized Electron-Dispersive Spectroscopy system, and (3) Inductively-Coupled Plasma Mass Spectroscopy. The sulphates most likely originated from coal-contained pyrite to form Fe(II) sulphates (melanterite, rozenite, and the most common szomolnokite), followed by Fe3+-rich sulphates (coquimbite group, copiapite group) and Al sulphates (alunogen, tamarugite). The halotrichite group and minor voltaite, metavoltine, and possibly secondary rozenite and szomolnokite were the last species to be formed. Strong enrichment in Al in copiapites and coquimbites, common occurrence of aluminocoquimbite, and Al likely entering the structure of Fe(II) sulphates makefurther phenomena, during which the initial ferrous copiapites were oxidized in the presence of Al-rich solutions, not out of the question. The obtained unit cell parameters sometimes stand for threshold values in the literature-based ranges drawn, but the values are usually below the 2% discrepancy. The Bhanine sulphates bear relatively large amounts of Tl, Hg, and Co when compared to Coal Clarke and mean crustal abundancies, being also moderately enriched in Ni and As.

Chemistry of monazites as provenance indicator - case study from the Upper Silesia Coal Basin (Poland)

Kusiak M.A., Bakun-Czubarow N.

Studia Geologica Polonica

2008

Vol. 129

107-130

Mineral chemistry and homogeneity, as well as crystal structure and unit cell parameters of detrital monazites isolated from sandstones of the Upper Silesia Coal Basin were studied using electron microprobe analysis (EPMA) and X-ray diffractometry (XRD). Analyzed monazite grains are chemically almost homogenous, only in a very few cases, parts of the grain are enriched in thorium and depleted in yttrium content. Typical feature of monazite from the Poruba Beds is relatively high content of Y (up to 4 wt. % Y2O3), what could point to higher temperature of crystallization. Monazite from the Kwaczała Arkose are, on average, richer in huttonite and slightly poorer in cheralite end-members than monazite from the Poruba Beds. Monazite from Kwaczała Arkose reveals the following unit cell parameters: a = 6.794(1) A*, b = 7.008(2) A*, c = 6.479(2) A*, b = 103.82(2)°, whereas for the Poruba Beds monazite these parameters, excluding b-value, are slightly higher: a = 6.804(3) A*, b = 7.002(5) A*, c = 6.488(4) A*, b = 103.85(3)°.