Siliceous earth occurs as a result of the Upper-Cretaceous and Early-Tertiary opokas and gaizes weathering. It is built mainly from the opal. Siliceous earth resembles diatomites in the physical features as: - a high porosity and absorptive capacity; - a refractoriness; - the acid activity resistance; - a high SiO2 content. It is used in a chemical industry as a carrier for catalysts, mineral fertilizers, herbicides, pesticides and fungicides in agriculture as well as a raw material for the refination and filtration and constituent of a synthetic moulding mass.
Deposits of siliceous earth occur mainly in tectonic troughs at the margin of the Holy Cross Mts. (Piotrowice and Dąbrówka deposits) and in the Lublin Upland (Lechówka deposit), in the form of sedimentary covers overlain by the Oligocene rocks.
Table 1 shows resources and the current state of exploration and development of siliceous earth deposits in Poland.
Anticipated economic resources of siliceous earth amounted to 2,223 thousand tonnes in 2017. Until recently, the exploitation has been temporarily carried out from Lechówka II deposit. Since 2014 the raw material has not been exploited and the resources have not changed in 2017.
Prepared by: Robert Bońda