Dipyramidal Molybdenite Crystals of Perga Ore District (Yastrubtsi Massif, Volyn Megablock of the Ukrainian Shield)
UDC 549.325.2 : 548 (477)
https://doi.org/10.15407/mineraljournal.37.03.037
V.O. Syomka (1), I.V. Kvasnytsya (2), S.M. Bondarenko (1), G.V. Syomka (1)
(1) M.P. Semenenko Institute of Geochemistry, Mineralogy and Ore Formation of the NAS of Ukraine
34, Acad. Palladina Pr., Kyiv-142, Ukraine, 03680
E-mail: syomka@igmof.gov.ua; sbond@igmof.gov.ua
(2) Taras Shevchenko Kyiv National University
90, Vasylkivska Str., Kyiv, Ukraine, 03022
E-mail: ikvasnytsya@gmail.com
Dipyramidal Molybdenite Crystals of Perga Ore District (Yastrubtsi Massif, Volyn Megablock of the Ukrainian Shield)
Language: Ukrainian
Mineralogical journal 2015, 37 (3): 37-44
Abstract: The rare dipyramidal crystals of molybdenite in alkaline metasomatites of the Yastrubtsi massif (Perga ore district in the Volyn megablock) have been found. This molybdenum mineralization is located in the areas of biotite-microcline-perthite metasomatites with fluorite. Size of molybdenite crystals reach 1—2 cm. Simple forms of molybdenite crystals are presented by dipyramids {101 - 6}, {101 - 7} and pinacoid. Taken together they form three types of habit of molybdenite crystals: dipyramidal with little development of pinacoid, pinakoidal with little development of dipyramid faces and transition type between them. The studied molybdenite crystals belong to the hexagonal polytype 2H with unit cell parameters a = 3.164 (1) and c = 12.311 (2) Ǻ. Lead is present as the impurity in molybdenite crystals. The cause of "dipyramidal" growth of molybdenite crystal could be a significant local saturation in mineral forming system that contributed more to the layering (0001) than the widening of the crystal in the same plane. Increased molybdenum content in alkaline metasomatites of exo- and endocontacts of the Yastrubtsi massif, is, probably, connected with metasomatic interaction of alkaline solutions, which is released during crystallization of melanocratic syenites of the central part (core) of the massif, with granitoids of Perga complex.
Keywords: molybdenite, morphology, polytype, trace elements, alkaline metasomatites, Yastrubtsi massif, Ukrainian Shield.
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