Crystal Morphology of Groutite (α-MnOOH) From the Zavallya Graphite Deposit (the Ukrainian Shield)

UDC 549.548. 521
https://doi.org/10.15407/mineraljournal.39.01.011

(1) KVASNYTSYA V.M., (2) NAUMENKO E.V.
(1) M.P. Semenenko Institute of Geochemistry, Mineralogy and Ore Formation of the NAS of Ukraine
34, Acad. Palladin Av., Kyiv-142, Ukraine, 03680
E-mail: vmkvas@hotmail.com
(2) National Museum of Natural History of the NAS of Ukraine
15, Bohdan Khmelnytsky Str., Kyiv, Ukraine, 01601
Language: Ukrainian
Mineralogical journal 2017, 39 (1): 11-18
Abstract: The morphology of crystals and aggregates of groutite from breccia-fractured zones of the Zavallya graphite deposit have been studied. Sizes of the largest crystals are up to 0.5—0.6 cm and its aggregates — several centimeters. In crystals of groutite with goniometer seven simple forms were found: rhombic prisms — {110}, {021}, {120} and {130}, pinacoids — {010} and {100}, rhombic dipyramid {111}. Such forms as {120}, {130} and {100} are secondary. There are six morphological types of groutite crystals with a different set of simple forms and the development of their faces, and several types of aggregates of crystals. Lens-shaped crystals of groutite are the most common ones, they make mainly its intergrowths and lumpy aggregates. There are elongated prismatic and needle-like prismatic groutite microcrystals along the [001] and up to 0.3 mm in size, their prismatic habitus determines the well-developed prism {110}. Expressive growth sculptures are characteristic of the faces of rhombic dipyramid {111} and rhombic prisms {021}. Polycentric growth on the faces of these forms and the formation of intergrowths and aggregates are the evidence of satiety of crystallization environment with manganese and of rapid growth of groutite crystals. Diagnosis of groutite is confirmed by X-ray diffraction and microprobe studies. The diffraction patterns of different groutite crystals are manifested by its characteristic reflexes. Groutite contains minor impurities Mo, Si, Al, P, Zn, Sc, As and Ba. It is often associated with quartz, seladonite, romaneshite, barite and calcite.
Keywords: groutite, crystal morphology, the Zavallya graphite deposit, Ukrainian Shield.
References:
1. Kostov, I. (1971), Mineralogy, Mir, Moscow, RU, 584 p.
2. Chukhrov, F.V. and Bonshtedt-Kupletskaya, E.M. (ed.) (1967), Mineraly, Sprav., Nauka, Moscow, RU, Vol. 2, Vyp. III, 676 p.
3. Skakun, L., Manchur, B. and Martyshyn, A. (2003), Mineral. zb., No 53, Vyp. 1-2, Lviv, UA, pp. 49-58.
4. Shpanov, E.P. (1970), Zap. Vsesoyuz. mineral. ob-va, Vol. 99, No 6, Leningrad, RU, pp. 749-751.
5. Fleischer, M., Richmond, W.E. and Evans, H.T. (1962), Amer. Miner., Vol. 47, No 1-2, pp. 47-58.
6. Gruner, J.W. (1947), Amer. Miner.,Vol. 32, No 11-12, pp. 654-659.
7. Klein, C. and Frondel, C. (1967), Amer. Miner., Vol. 52, No 5-6, pp. 858-860.
8. Majmundar, H.H. (1969), Canad. Miner., Vol. 9, pp. 718-720.
9. Segeler, C.G. (1959), Amer. Miner., Vol. 44, No 7-8, pp. 877-878.

English