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 material is being increasingly replaced by lime meals doming from the processing of limestones and marbles and by a raw material gained from the 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 Cretaceous sediments in the Lubelszczyzna area and in the area of north-eastern Poland where Cretaceous deposits occur in the form of ice floats within 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. Except for carbonates, lacustrine sediments contain the organic matter and the material brought from the land. Lacustrine chalk and gyttja usually contain minimum 80% of calcium carbonate (CaCO3), whereas the sediment containing 50-80% of calcium carbonate is called as calcerous 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 overburden of the exploited brown coal beds.
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 2020 amounted to 206.617 million tonnes, including 36.010 million tonnes (17.4% of the total resources) of proper (“writing”) chalk and 170.607 million tonnes (82.6%) of lacustrine chalk and calcareous gyttja. The resources decreased by 0.202 million tonnes (it means by 0.1%) in comparison with the previous year.
In 2020, there was 1 new deposit included in “The balance…” – Kornica Nowa III (0.049 million tonnes) located in Mazowieckie Voivodeship (the exploitation started in 2020).
The output of chalk in 2020 was carried out from 12 deposits and amounted to 0.239 million tonnes. The volume dropped by 0.071 million tonnes in comparison with 2019 (that is by 22.9%). The exploitation of proper chalk was carried out from 9 deposits. The output was equal 0.206 million tonnes (86% of the total chalk output) – by 0.064 million tonnes (24%) less than in 2019. Lacustrine chalk was recovered from 3 deposits. The exploitation amounted to 0.033 million tonnes (14% of the total domestic output). The output decreased by 0.007 million tonnes (17%) in comparison with 2019.
Lacustrine chalk is also temporarily recovered from the overburden of brown coal beds in the vicinities of Bełchatów. In 2020 from Bełchatów-pole Szczerców deposit there were 0.007 million tonnes of lacustrine chalk exploited (the amount is not included in the Tables 1 and 2).
The economic resources of chalk are currently documented for 8 deposits and amount to 12.917 million tonnes which accounts for 85.8% of the total anticipated economic resources of these deposits. In comparison with the previous year the economic resources decreased by 1.071 million tonnes (7.7%). The drop resulted from: - the exploitation and losses; - the crossing out from “The balance…” the resources within the abolished mining area Dębina III (-0.906 million tonnes); - the establishing of economic resources in the newly documented Kornica Nowa III deposit (+0.039 million tonnes).
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 1989-2020.
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].