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)

Table 2. X-Ray Diffraction Data for Bauxite from Nézsa Zr-Filtered Molybdenum Ka Radiation Pisolitic hauxite Bauxitic clay d(A) I Mineral d(A) I Mineral 7.1 C) 27 Kaolinite 7.15 100 Kaolinite 5.00 9 Goethite 4.96 7 Goethite 4.71 13 Diaspore 4.45 33 Kaolinite 4.44 37 Kaolinite 4.35 37 Kaolinite 4.17 44 Goethite, Kaolinite 4.17 70 Goethite, Kaolinite 1.00 100 Diaspore 3.98 17 Diaspore 3.84 27 Kaolinite 3.81 15 Kaolinite 3.07 43 Hematite 3.57 84 Kaolinite 3.58 56 Kaolinite 3.52 19 Anatase 3.52 37 Anatase 3.37 12 Kaolinite 3.37 16 Kaolinite 2.68 15 Goethite 3.24 12 Rutile 2.55 22 Kaolinite, Diaspore 2.70 81 Hematite, Goethite 2.49 30 Kaolinite 2.5G 58 Diaspore, Kaolinite 2.44 30 Goethite 2.52 80 Hematite, Kaolinite 2.38 11 Kaolinite 2.3 G GG Diaspore 2.33 30 Kaolinite 2.32 93 Diaspore, Kaolinite 2.29 22 Kaolinite 2.21 27 Hematite 2.24 8 Kaolinite 2.15 65 Diaspore, Kaolinite 2.19 15 Kaolinite 2.08 60 Diaspore 2.13 5 Kaolinite 2.03 23 Kaolinite 1.99 20 Kaolinite The deposit overlies the "Dachsteinkalk" of Upper Carnian age. According to data of deep-drilling carried out in 1950, the size of the deposit is as follows: maximal thickness, 28 m., maximal length, 200 m., maximal width, 60 m. It is overlain by Middle Eocene Miliolina limestones, Oligocène sandstones, clays and Quaternary scree and loess. The deposit consists of high-grade bauxites irregularly alternating with clayey bauxites and bauxitic clays. In the western part of the exposure the bauxitic clay contains white pure kaolinite nodes. The colour of the bauxites is also of great variety: greyish-white, yellow, red, brownish-red. As to texture, an irregular alternation of pisolitic and homogeneous bauxites can be observed. According to the above-mentioned characteristics, the Nézsa bauxite deposit is of a reworked type. The age of the bauxites at Nézsa is thought to be Lower Cretaceous, similar to that of the Transdanubian bauxites. Earlier mineralogical investigations Our knowledge about the mineralogy of the Nézsa bauxites has been very incomplete till now except for some micromineralogical data.