General information and occurrence
Chalk is a calcareous, soft and porous sedimentary rock characterized by a high calcium carbonate (CaCO3) content and a very fine-grained structure. It is used mainly i.a.: rubber, paper, chemical, pharmaceutical, cosmetic, ceramic and cement industries; for the production of paints and lacquers, plastic, building materials, in the agriculture as a fertilizer chalk for the soil liming and as a fodder chalk for the animals breeding. The natural raw materials of a given characteristic and use are being also obtained as a result of milling of other types of limy rocks and through a process of solutions precipitation.
In Poland, chalk is the name traditionally given to two different mineral raw materials: proper chalk rock (still often called as ”writing chalk” in Polish literature) and lacustrine chalk (calcareous tufa). The raw materials differ in an origin, a chemical composition and use.
The proper chalk is an organogenic marine sediment of a white or creamy color constituted mainly from the planktonic organisms remains: coccoliths and crusts of forams. In Poland, it occurs in the Cretaceous sediments in the Lubelszczyzna area and in the area of north-eastern Poland where the Cretaceous deposits occur in the form of ice floats within the Quaternary sediments. In the vicinities of Kornica and Mielnik on the Bug river on the border of Mazowieckie and Podlaskie Voivodeships there have been 22 deposits of “writing chalk” documented, and 1 deposit in Pomorskie Voivodeship. In the Lubelszczyzna area, in the vicinities of Chełm. “writing chalk” is exploited for the cement production. The deposits occurring in this region are presented in the chapter Limestones and marls for cement and lime industries.
The lacustrine chalk is usually of white, white-yellow or grey color and is a very humid, clammy mass. It originates from the biochemical precipitation and the accumulations of a carbonate sediment on the lake bottoms. The significant role in this process play plants which pick up a dissolved calcium dioxide (CO2) from water. This results in solution saturation changes and a calcite crystallization. Sediments of this type contain mainly carbonates and organic matter and detritic material brought from the land. The name of “lacustrine chalk” is used for the sediments with the minimum content 80% of calcium carbonate (CaCO3), whereas the sediment containing 50-80% of calcium carbonate is called as calcareous gyttja. Very often the lacustrine chalk and gyttja beds occur below the peat beds. It results from the shallowing and encroachment of a sedimentary reservoir (lake). The lacustrine chalk deposits in Poland are usually of the Quaternary age and occur mainly in northern and north-western Poland. The Neogene chalk accumulations are known in the Bełchatów vicinities where they occur within the tectonic structure called as Kleszczów trough. The formations filled this trough contain the brown coal beds which are the subject of exploitation.
The chalk deposits occurrence is presented on the map.
According to the Regulation of the Minster of the Environment of the 1st of July 2015 on the geological documentation of a raw material deposit, excluding a hydrocarbon field (number of Polish act: Dz. U. 2015, poz. 987) the limit values of the parameters that defines the deposit and its boundaries (Appendix 8) are:
- lacustrine chalk and calcareous gyttja (table 38) are documented with the minimum deposit thickness of 1 m, the maximum ratio of overburden to the deposit thickness of 0.3 and the minimum general alkalinity expressed per CaO in dry mass of 40%
- proper (“writing”) chalk (table 39) is being documented to the maximum depth of 70 m, with the maximum overburden of 15 m, the maximum ratio of overburden to deposit thickness of 0.2 and the minimum weighted average of the CaCO3 content in a deposit profile of 80%.
Resources and output
Table 1 shows resources and the current state of the exploration and development of chalk.
The total anticipated economic resources of chalk and calcareous gyttja in 2021 amounted to 206.303 million tonnes, including 35.752 million tonnes (17.3% of the total resources) of proper (“writing”) chalk and 170.551 million tonnes (82.7%) of lacustrine chalk and calcareous gyttja. The resources decreased by 0.314 million tonnes (it means by 0.2%) in comparison with the previous year.
In 2021, any new decision approving a geological documentation or a supplement to such a documentation was issued, therefore any resources changes were recorded.
The output of chalk in 2021 was carried out from 12 deposits and amounted to 0.302 million tonnes. The volume increased by 0.063 million tonnes in comparison with 2020 (that is by 26%). The exploitation of proper chalk was carried out from 9 deposits. The output was equal 0.258 million tonnes (85% of the total chalk output) – by 0.052 million tonnes (25%) more than in 2020. Lacustrine chalk was exploited from 3 deposits. The exploitation amounted to 0.044 million tonnes (15% of the total domestic output). The output increased by 0.011 million tonnes (33%) in comparison with 2020.
Lacustrine chalk (and other “accompanying raw materials”) is also temporarily recovered from the overburden of brown coal beds in the vicinities of Bełchatów – in the course of preparing the beds for the exploitation. In 2021 from the Bełchatów-pole Szczerców deposit there were 0.049 million tonnes of chalk exploited (the amount is not included in the Tables 1 and 2).
The economic resources of chalk are currently documented for 8 deposits (from which 6 deposits were exploited in 2021) and amount to 12.662 million tonnes which accounts for about 86% of the total anticipated economic resources of these deposits. In comparison with the previous year the economic resources decreased by 0.255 million tonnes (2%).
Most of the chalk and calcareous gyttja deposits are located within the Lakelands areas in Wielkopolska region, on Lubusz Land, on Pomerania region, on Masuria region, on Warmia region and on Suwalszczyzna region. These are also the prospective areas of the raw material occurrences*.
The figure given below shows changes in domestic resources and production of chalk in Poland in the years 1989-2021.
Prepared by: Wojciech Szczygielski
* Jurys L., 2020 - "Kreda jeziorna i gytia wapienna (lacustrine chalc)". In: "Bilans perspektywicznych zasobów kopalin Polski wg stanu na 31.12.2018 r." (eds. Szamałek K., Szuflicki M., Mizerski W.): 368-370. PIG-PIB, Warszawa [in Polish].