The Jurassic kaolinite-illite clays in Rozwady (Opoczno region) were exploited for the needs of the chamotte fireclay refractories plant in Opoczno built in the years 1926–1928. Until the World War II, these clays were a major component of ceramic sets used for manufacturing quartz-chamotte refractories applicable to steel-making ladles in the Upper Silesian steel works. In the year 1990, due to a drastically low demand for chamotte refractories in Poland, both the plant in Opoczno and the Mroczków-Rozwady clay underground mine were shut down. However, recent years have brought about a renewed interest in exploiting the Opoczno clays for the domestic ceramic industry. Clay mining was initiated in 2014 in the new open pit in Borkowice and has also continued as of 2017 exploiting the Rozwady I deposit. In the clay raw material of Rozwady, kaolinite clearly predominates over illite, among the non-clay minerals quartz occurs in variable quantities, whereas the organic matter is a permanent but minor component. The quantity of the organic matter varies within the deposit and forms the basis to distinguish light and dark colored clays. Considering the petrographical reasons, the raw material of Rozwady represents rocks intermediate between claystones and mudstones. The Rozwady clays have been used by many plants producing tiles within the Opoczno region and it is predicted that their use will increase, as the prices of the clay raw materials imported from Ukraine is constantly growing and the cost of their transport is substantial.

The paper discusses the issue of the utilization of selected raw materials obtained as by-products of rock mining and processing in the ceramic industry in Poland. The raw materials in question are: kaolinite-rich clayey substance remaining after quartz sand washing and alkalis-rich finest fractions generated in the course of the production of granite crushed aggregates. Despite usually high content of coloring oxides, they have been utilized for the production of ceramic goods, the high whiteness of which is not required after firing. High interest in these materials was connected with the implementation of the fast firing method as well as modernization and large scale expansion of the domestic ceramic industry, especially ceramic tiles and sanitaryware sectors. Between the mid-1990s and 2018, the annual consumption of kaolinite raw materials being by-products of quartz sand washing increased from ca. 20,000 to 100,000–120,000 Mg. At the same time the sales of secondary granite fractions utilized as a flux in the ceramic industry rose from 30,000 to 120,000 Mg per year in 2007–2008, and 50,000–70,000 Mg per year most recently. The development of the utilization of these raw materials has been an example of the rational and comprehensive management of all the minerals that occur in deposits in operation. This is particularly important in the context of the depletion of these raw materials reserves and the limited availability of their new deposits. Furthermore, this also makes a contribution towards reducing the scale of imports of raw materials for the ceramic tile industry, which is inevitable due to insufficient supplies from domestic sources.

Feldspar raw materials belong to such raw materials for which demand has risen in Poland in the last years to a largest extent. The reason of it is the expansion of domestic branch of ceramic tiles. Larger and larger demand of the Polish industry of ceramic tiles for feldspar raw materials is covered among others in greater and greater extent by import from Turkey. Feldspar raw materials in that country are mainly obtained from albite-rich rocks which occur in the west part of the country in Menderes Massif particularly in its south fragment (Submassif Çine). Their exploitation and proccessing are carried out by many companies from which KALTUN, ESAN ECZACIBASI, ÇINE AKMADEN, KALEMADEN and ERMAD are of the greatest importance in the Polish market. The raw material of the highest quality [...] is obtained as a result of benefication of primary rocks by flotation. The main compounds - apart from quartz - of studied samples analized by means of microscopic method are feldspars represented first of all by albite. This mineral occurs in two varieties. First of them - which strongly dominates - is so called chessboard albite. This variety is formed as a result of albitization of feldspars of various types. On the other hand, typical, multitwinned crystals of this mineral are observed significantly rarer. Albite most often contains 5-10 mol.% of anorthite molecule. Sporadically minor and/or trace minerals (e.g. titanite, rutile, micas) occur in samples studied. They are the carriers of colouring oxides (Fe2O3, TiO2) presence of which is outstandingly undesirable, especially in raw materials for the production of ceramic tiles of the highest quality such as gres porcellanato. The characteristic feature of the Turkish feldspar raw materials is occurrence of minor or trace amount of TiO2 in domination compared to Fe2O3 which mostly is more common colouring oxide in feldspar raw materials. It is connected with sporadic occurrence of such titanium minerals as titanite [...] and rutile TiO2. However, in the majority of investigated samples the presence of these carriers of colouring oxides was not stated which confirms the opinion about high quality of feldspar raw materials of Turkish production.