An "unknown Ni-Al hydrosilicate" was found in the karstic nickel deposits in the localities Ba and Takovo in Serbia, and Aghios Ioannis in Greece. It occurs in fine-grained bluish-green and green aggregates with takovite and hydrated halloysite. It is an epigenetic product in the karstic nickel deposit. X-ray powder diffraction (XRPD) data are indexed with a monoclinic unit cell, a = 8.524 (4), b = 7.490 (3), c = 24.214 (6) Å, b = 104.55 (6)°, V = 1545.9 Å3. The thermal study has shown a characteristic dehydroxylation effect at 450 °C, which distinguishes this mineral from takovite and halloysite. The infra-red technique is very sensitive for the detection of the "unknown Ni-Al hydrosilicate": an absorption band between 1250 cm-1 and 1270 cm-1 is very characteristic for this mineral. From chemical analyses of the admixture of this mineral and hydrated halloysite in different proportions from the Aghios Ioannis deposit in Greece, after removal of impurities, the calculated formula is close to Ni2.00 Al2.00 (Si1.93 Al0.07) on the basis of 12 (O,OH).
Authors:Máté Zsigmond Leskó, Richárd Zoltán Papp, Boglárka Anna Topa, Ferenc Kristály, Tamás Vigh, and Norbert Zajzon
carried out in the Institute of Mineralogy and Geology, University of Miskolc.
X-ray powder diffraction (XRPD) measurements were carried out using a Bruker D8 Advance diffractometer. The measurement parameters were the following: CuKα radiation, 40
The present article discusses the applicability of thermoanalytical methods in the analysis of Hungarian soils formed on carbonate rocks. Up to now only limited mineralogical and soil chemical research has been done on these soils. Soils from the Bükk Mountains, the most varied limestone region in Hungary, were used for the investigations. The aim was to extend our incomplete knowledge on the mineral composition and formation processes of these soils and to demonstrate the possibilities and evaluation potential of thermoanalytical techniques. All the soils investigated were formed on limestone and had different surface soil thickness, influenced by the accumulation of silicate debris and the microterrain. The results of soil mineralogical analysis revealed an extraordinarily high proportion of quartz compared to that of other minerals (especially calcite), indicating that these soils could not have originated solely from the weathering of the limestone bedrock. The results also showed that thermoanalytical methods could complement classical chemical and instrumental (XRPD) methods in research on the genesis of soils formed on limestone.