Szekessy Vilmos (szerk.): A Magyar Természettudományi Múzeum évkönyve 55. (Budapest 1963)
Kaszanitzky, F.; Rózsavölgyi, J.: Halloysite pseudomorph after calcite from Gyöngyösoroszi
ANNALES HI STÛRICO-NATURALES MUSEI NATIONALIS HUNGARICI Tomus 55. PARS MINERALOGICA ET PALAEONTOLOGICA 1963. Hailoysite Pseudomorph after Calcite írom Gyöngyösoroszi By F. KASZANITZKY and J. RÓZSAVÖLGYI, Budapest The ore occurrence mentioned in the title lies in the western part of the Mts. Mátra, in NE Hungary. The ore deposit was formed near the surface, by the action of ascending mesothermal and epithermal solutions. Halloysite is known from Gyöngyösoroszi since 1953. The white, unguentous material was found in the first 300 m of the main gallery. Identification of the material was made by E. NEMËCZ (3). In 1961, M. NAGY , master miner, collected halloysite, in the course of prospective work (Aranybányabérc-vein, + 400 level, 5—6 fronts), and the material was dispatched to the authors. It is an interesting feature of the find that halloysite is a pseudomorph after calcite in the site designated above. The examined specimen originates from the subsurface oxydated zone of the vein. It is a hand-sized, cauliflower-shaped aggregate, composed of 10—12 mm long, flat, elongated pieces in a hypoparallel situation. As regards crystalline forms, one can recognize the dumped rhombohedron. In a similar development, calcite is frequent in the site. The internal structure of the specimen consists of a collection of thin lamellae. The material can be easily crushed by hand; its colour white with a slight yellowish tint. The aggregate is covered by an easily removable amorphous crust, one-tenth mm deep. We prepared some X-ray, I)TA, and electron-microscopic photographs of the material. The X-ray graph (8 mA, 34 KV, 8 hours; unfiltered Fe ka/ 3 radiation; radian chamber; plastic tube preparation) showed the following minerals: I. rfhki Á Mineral Medium strong 4,90 Hydrargyllite Very strong 4,41 Halloysite, hydrargyllite Medium strong 2,58 Halloysite Weak 2,41 Hydrargyllite Verv weak 2,22 Halloysite Very weak 1,967 ? Medium strong 1,680 Halloysite Medium strong 1,629 Halloysite Very strong 1,480 Halloysite Very weak 1,441 Hydrargyllite Medium strong 1,280 Halloysite Medium strong 1,234 Halloysite
