Fly ash samples from the five steam electric power stations of the Lignite Center of Western Macedonia were used in this study. They consisted mainly of anhydrite, lime, quartz and amorphous material as well as feldspars, calcite, micas + clays, portlandite and gehlenite which were all present in minor amounts. Anhydrite, lime and portlandite in the fly ash samples diminished upon treatment wit...

Fine scale heterogeneities in strontium isotope ratios, 40Ar-39Ar ages, and chemical com~sition have been determined for individual mineral grains and enclaves in the rhyolites of San Vincenzo, Italy. The rhyolites are peraluminous with phenocrysts of alkali feldspar, piagioclase, biotite, and cordierite and have previously been divided into two groups on the basis of whole rock major element c...

The effective utilization of fly ash (FA) as a raw material for ceramics production is performed on the FA-kaolin mixtures containing kaolins 10% by mass. in comparison with FA and three were annealed to mullite at temperatures 1000, 1100, 1200 1300 °C. main aims contribute discussion effect impurity Na,K-feldspars Fe2O3 sintering procedure, porous properties structural properties. phases chara...

The colours of many feldspars are enhanced by natural radiation. The same phenomenon can be simulated by X-ray radiation in the laboratory. The changes of colour and the formation of defect centers in different feldspars including one microcline (amazonite) after X-ray irradiation has been investigated using e.p.r. spectroscopy [1]. The main colours of amazonite are green, bluish green and blue...

Electrostatic calculations estimated the energy of hypothetical ion clustering in intermediate plagioclase feldspars. The calculated energy appears too great to allow segregation of Ca and Na atoms into domains upon annealing without a corresponding movement of A1 and Si from an original disordered structure. The calculated energy may be sufficiently small that Ca and Na atoms can disorder part...