Siliceous earth resembles diatomites in physical features and, therefore, finds similar use in the industries. It is used as carrier for catalysts in chemical processes and for mineral fertilizers and herbicides, pesticides and fungicides in agriculture as well as raw material for refination and filtration and constituent of synthetic moulding mass. Siliceous earth differs from diatomites in the mode of origin as it is the product of decalcification of opoka sedimentary rocks and mainly built of opal, a mineraloid gel.
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 Oligocene rocks.
The Lechówka and Piotrowice deposits have similar quality parameters – apparent density between 263 and 371 g/l, R2O3 content in the range of 5.5 – 7.0 %. The Dąbrówka deposit has worse parameters - R2O3 content above 8.0 % and average apparent density 580 g/l.
Table 1 shows resources and the current state of exploration and development of siliceous earth deposits in Poland.
Anticipated economic resources amounted to 2,223 thousand tonnes in 2012 (almost 50 % in A+B+C1 categories). Domestic demand for siliceous earth is fully covered by import.
Prepared by: Robert Bońda