Morphological and chemical characteristics of amphibole crystals in desilicated pegmatites, Rila Mountain, SW Bulgaria

The desilicated pegmatites from the area of the Urdini lakes, Northwest Rila Mountain intersect ultramafic bodies, occurring among high-grade metamorphic basement of the Rila-Rhodope batholith. The following rock-forming minerals are characteristic – plagioclase (mainly oligoclase), phlogopite, amphibole, actinolite, tremolite, anthophyllite, chlorite and others. Minerals from the amphibole supergroup are studied using optical, X-ray diffraction, X-ray spectral and chemical methods. Their morphology and crystal chemistry are characterized as well as their classification and nomenclature position are determined. Actinolite, tremolite, anthophyllite and Mg-hornblende from the amphibole supergroup are identified. The trends and variations in the chemical composition at their central and peripheral sections have been clarified.