Kaszab Zoltán (szerk.): A Magyar Természettudományi Múzeum évkönyve 63. (Budapest 1971)

Embey-Isztin, A.: Contribution to the mineralogy of the bauxites from Nézsa (North-Hungary)

According to the earliest investigations of NÁRAY—SZABÓ and NEUGEBAUER (1944), the main bauxite minerals are diaspore and hematite. Qualitative and quantitative micromineralogical investigations were carried out by J. Kiss (1952). His heavy-mineral data have been used also in the present work. Further results worth mentioning are the thermal analyses in works of M. FÖLDVÁRI & VOGL (1953) and T. GEDEON (1953). Investigation methods To gain a more detailed knowledge about the mineralogy of the bauxite qualitative and quantitative X-ray analytical investigations of a number of typical bauxite samples were carried out and checked by chemical analyses (Tables 1—5). The TG, DTG and DT analysis and the colour analysis by heating proved also suitable as supplementary check methods. In addition, a number of electron microscopic and polarisation microscopic investigations have been made. In quantitative X-ray diffraction analysis the NÁRAY-SZABÓ & PÉTER method was used, which was first applied to bauxite investigation by BÁRDOSSY (1966). This provides reliable results only if the so-called "mineralogical error" is corrected for. In the present case the peak intensities of pure kaolinite were used to subtract Table 3. X-ltay Diffraction Data for Bauxite from Nézsa Zr-Filtered Molybdenum Ka Radiation Bauxite containing calcite Bauxitic clay d(A) I Mineral d(A) I Mineral 7.15 38 Kaolinite 7.16 60 Kaolinite 4.36 46 Kaolinite 4.99 7 Goethite 4.17 44 Kaolinite, Goethite 4.71 10 Diaspore 3.99 60 Diaspore 4.35 63 Kaolinite 3.85 33 Kaolinite, Calcite 4.17 71 Kaolinite, Goethite 3.67 30 Hematite 4.00 30 Diaspore 3.58 69 Kaolinite 3.83 36 Kaolinite 3.24 12 Rutile 3.74 29 Kaolinite 3.03 100 Calcite 3.57 100 Kaolinite 2.84 3 Calcite 3.52 30 Anatase 2.69 62 Hematite 3.38 56 Kaolinite 2.55 55 Diaspore, Kaolinite 3.24 16 Rutile 2.52 81 Hematite, Kaolinite 2.69 18 Hematite 2.34 68 Diaspore, Kaolinite 2.54 45 Kaolinite, Diaspore 2.29 55 Kaolinite, Calcite 2.50 50 Kaolinite, Hematite 2.20 21 Hematite 2.44 25 Goethite 2.13 25 Diaspore, Kaolinite 2.32 65 Kaolinite, Diaspore 2.09 19 Calcite 2.29 10 Kaolinite 2.07 30 Diaspore, Hematite 2.19 13 Kaolinite 1.91 33 Calcite 2.13 12 Kaolinite, Diaspore 1.89 36 Calcite, Kaolinite 2.06 8 Kaolinite, Diaspore