Buseck P. R.

Lovas György A.

Nagy T.

Pósfai Mihály

Weiszburg Tamás G.

English

University of Szeged

Acta Miner alogica-Petrographica, Szeged, XLi, Supplementum, 2000 RE-EXAMINATION OF MÁTRAITE FROM THE TYPE LOCALITY, GYÖNGYÖSOROSZI, MÁTRA MTS., HUNGARY WEISZBURG, T.G. (Dept. of Mineralogy, Eötvös L. University, Budapest, Hungary), PÓSFAI, M. (Dept. of Earth and Environmental Sciences, University of Veszprém, Veszprém, Hungary), BUSECK, P.R. (Dept. of Geology and Chemistry/Biochemistry, Arizona State University, Tempe, AZ, USA), NAGY, T. & LOVAS, Gy. (Dept. of Mineralogy, Eötvös L. University, Budapest, Hungary) E-mail: weiszburg@ludens.elte.hu ZnS crystals with peculiar conical-pyramidal morphology were described from Gyöngyösoroszi, Hungary by KOCH (1958) and reported as representatives of a new polymorph of ZnS. Based on similarities of X-ray diffraction patterns (taken in a 114.6 mm oscillation camera) SASVÁRI (1958) suggested that these crystals are the natural counterparts of the 3R rhombohedral modification of ZnS reported by BUCK & STROCK (1955). The 3R structure was supposed to be the result of a slight distortion of the cubic close-packed, 3C sphalerite structure. The new natural ZnS polymorph was given the mineral name mátraite. WEISZBURG & LOVAS (1982) studied the type material of mátraite by applying a broader range of single crystal X-ray diffraction techniques. They concluded that mátraite could not be a 3R modification, predicted strong real structure effects and suggested further TEM studies. Recently we found again ZnS crystals of mátraite type morphology on samples from Gyöngyösoroszi. Our combined X-ray diffraction, optical, scanning and transmission electron microscopy study revealed that the "mátraite" crystals have a densely twinned 3C sphalerite structure, similar to the "pyramidal type" ZnS that was also reported from Gyöngyösoroszi (PÓSFAI et al., 1988). These results indicate that mátraite should be regarded as a morphological variety of sphalerite having a characteristically disordered (twinned) structure. Nomenclatural consequences of the present results are under preparation for IMA CNMMN. This work was partly supported by OTKA Grant # T016628. References BUCK, C.C. & STROCK, L.W. (1955). American Mineralogist, 40: 192-200. KOCH, S. (1958). Acta Mineralógica Petrographica, Szeged, 11:11-22. PÓSFAI, M., DÓDON Y, I. & SOÓS, M. (1988). Neues Jahrb. Mineral. Monatsh. 438-445. SAS VÁRI, K. (1958). Acta Mineralógica Petrographica, Szeged, 1 1: 23-27. WEISZBURG, T. & LOVAS, Gy.A. (1982). Annales Univ. Sci. Budapestiensis, Sectio Geologica, 24: 47-52. 124 

Re-examination of Mátraite from the type locality, Gyöngyösoroszi, Mátra Mts., Hungary

http://acta.bibl.u-szeged.hu/25019/1/mineralogica_041_suppl_124.pdf

Re-examination of Mátraite from the type locality, Gyöngyösoroszi, Mátra Mts., Hungary

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