Spatial Modelling of Kaolin Deposit Demonstrated on the Jimlíkov-East Deposit, Karlovy Vary, Czech Republic

The present study is focused on spatial modelling of a kaolin deposit in Karlovy Vary, Czech Republic, and the methodical procedure of development, evaluation and visualization of a 3D model are described step by step. The implementation of this methodology is performed in Visual Studio 2019 with use of the Surfer and Voxler objects from Golden Software. This methodology combined with the newly developed software (Kaolin_A and Kaolin_Viz programs) allow a user to create a variant dynamic model for the same or similar types of deposits. It enables a quick update of the model when changing the input data, based on the new mining exploration or when changing the modelling parameters. The presented approach leads to a more advanced evaluation of deposits, including various estimates of reserves according to pre-specified usability conditions. The efficiency of the developed methodology and the software for the evaluation of the deposit are demonstrated on the kaolin deposit Jimlíkov-East, located near the village Jimlíkov about 5 km west of Karlovy Vary in the Czech Republic.

Genesis of Meka’a Geophagic Kaolin Deposit (In Foreke-Dschang West Cameroon)

Geological, mineralogical and geochemical studies where carried out on Meka’a kaolin deposit located in Foréké-Dschang in order to define the ore genesis. Three kaolin facies (yellow, red and white) and isalteritic components were characterized by different methods including morphostructural description, XRD, XRF, ICP-MS, SEM-EDS, heavy mineral research and organic matter contents. The results show that all these kaolins are based on kaolinite (87–90%) associated with more or less significant phases of orthoclase (1-2%), goethite (0.5-3.5%), quartz (1-1.5%), anatase (1.2-2%) and hematite (1-2%). Small amounts of illite (3.5%) was found only in white facies. The scanning electron microscope (SEM) pattern shows that kaolinite particles contained in these kaolins are very small (<2 µm) and are poorly crystallized due to the impurities they contain. Meka’a kaolin’s are extremely weathered (CIA and CIW ≈ 100) and their organic matter content is considerable (1.82-2.54%) and is explained by the presence of carbonized wood in the ignimbrites. The combination of different analytical techniques points out a meteoric weathering of ignimbrite under oxidizing conditions as being of petrogenetic origin of this kaolin deposit.

Microbial nitrification and acidification of lacustrine sediments deduced from the nature of a sedimentary kaolin deposit in central Japan

Kaolin deposits in the Seto-Tono district, central Japan, were formed by intense kaolinization of lacustrine arkose sediments deposited in small and shallow inland lakes in the late Miocene. Based on mineralogical and stable isotopic (Fe, C, N) studies of Motoyama kaolin deposit in the Seto area, we concluded that it was formed by microbial nitrification and acidification of lacustrine sediments underneath an inland lake. Small amounts of Fe–Ti oxides and Fe-hydroxide in the kaolin clay indicated that iron was oxidized and leached during the kaolinization. The field occurrences indicate that leached ferric iron precipitated on the bottom of the kaolin deposit as limonite crusts, and their significantly fractionated Fe isotope compositions suggest the involvement of microbial activity. The C/N ratios of most of the kaolin clay are distinctly higher than those of modern lacustrine sediment. Although, the possibility of a low-temperature hydrothermal origin of the kaolin deposit cannot be completely ruled out, it is more likely that acidification by dilute nitric acid formed from plant-derived ammonia could have caused the kaolinization, Fe oxidation and leaching. The nitrate-dependent microbial Fe oxidation is consistent with dilute nitric acid being the predominant oxidant.