Ceramic clays are generally represented by sedimentary clays of marine or lacustrine origin and with minerals of the kaolinite and illite group as the major rock-forming components. The clays, also known as kaoline rocks, are raw material for production of whiteware ceramics such as porcelain and bone china.
From the point of view of process technology, the fired products may be assigned to whiteware and stoneware. Whiteware ceramic clays, attaining almost 50 % whiteness when fired at temperature of 1,300o C, are used to produce porcelite and faiance. In turn, stoneware products are characterized by very low level of water absorption and high mechanical and chemical resistance.
The majority of deposits of ceramic clays occur in the Lower Silesian region (Bolesławiec Clays) and the Świętokrzyskie Voivodeship. The Bolko II, Janina and Ocice deposits of white firing stoneware clays are related to intercalations of kaolinite clays in sandstones of the Upper Cretaceous.
The other lithological type includes ceramic clay deposits such as Nowe Jaroszowice and Janina-Zachód and Janina I. These deposits are related to poorly coherent sandstones with cement rich in kaolinite. The usable fraction is separated from these rock by water-washing and the obtained concentrate contains about 30 % of kaolinite clay.
Ceramic clays deposits are presented on the map.
Table 1 shows the current state of exploration and development of the above discussed deposits.
In 2011 anticipated economic resources of whiteware ceramic clays amounted to 59.2 million tonnes and decreased by 0.14 million tonnes.
In 2011, production of white firing ceramic clays was equal 130.88 thousand tonnes and was coming from the Janina I deposit only. List of deposits is presented in table 2.
Stoneware ceramic clays occur in the Lower Silesian region and central parts of the country.
In 2011 anticipated economic resources of stoneware ceramic clays amounted to 77.12 million tonnes and decreased by 0.22 million tonnes.
Table 3 shows the current state of exploration and development of these deposits.
In 2011, production of stoneware ceramic clays was equal 215 thousand tonnes (increased by 16 %) and was coming from three deposits - Zebrzydowa Zachód, Paszkowice and Baranów. List of deposits is presented in table 4.
Prepared by: Janina Dyląg