Chalk

Chalk is a weakly coherent and porous limestone rock, mainly used in the manufacture of rubber, paper, chemicals, dyes and cement. Cretaceous limestones of the chalk type used in production of cement (Chełm deposit) are discussed in the section dealing with limestone and marl raw material of the cement industry. Chalk deposits found in north-eastern Poland are related to erratics of Cretaceous chalk embedded in Quaternary glacial sediments (for example, the Mielnik and Kornica deposits).

In Poland, chalk is the name traditionally given to two different mineral raw materials: lacustrine chalk (calcareous tufa) and proper chalk rock (still often called as ”writing chalk” in Polish literature). The raw materials differ in origin and chemical composition and use.

Lacustrine chalk, also known as ”meadow limestone” or ”lacustrine limestone”, is a calcareous sediment of the Quaternary age, associated mainly with post-lacustrine series formed in times of the Last Glaciation. It is used in agriculture as calcareous fertilizer. Accumulations of lacustrine chalk occur mainly in northern and north-western Poland, often at the base of peat and calcareous gyttja deposits. Chalk deposits occurrence is presented on the map.

According to the Regulation of the Minster of the Environment of the 1^st of July 2015 (number of Polish act: Dz. U. 2015, poz. 987) the limit values of the parameters that defines the deposit (Appendix 8) are:

• lacustrine chalk and calcareous gyttja (table 38) are documented with minimum deposit thickness of 1 m, maximum ratio of overburden to deposit thickness of 0.3 and minimum alkalinity (CaO) of 40% (71.2% CaCO₃);
• proper (“writing”) chalk (table 39) is being documented to the depth of 70 m, with maximum overburden of 15 m, maximum ratio of overburden to deposit thickness of 0.2 and minimum alkalinity (CaO) of 44.8% (80% CaCO₃).

Table 1 shows resources and the current state of exploration and development of chalk.

Table 1. Chalk - million tonnes

Anticipated economic resources of chalk calcareous gyttja in 2015 amounted to 199.99 million tonnes and increased by 0.106 million tonnes (0.05%) in comparison with the previous year.

There were two new deposits included in “The balance…” (both located in Mazowieckie Voivodeship): newly-documented Sewerynów 1 deposit (0.697 million tonnes of proper chalk) and Kornica – Nowa 1 deposit (1.145 million tonnes of proper chalk) – allocated from Kornica – Nowa deposit.

There were new documentations with recalculated resources approved for four deposits: Kornica – Nowa (-1.734 million tonnes, from that 1.145 million tonnes allocated as the new Kornica – Nowa 1 deposit and 0.590 million tonnes as a result of better exploration), Malinowo-pole IV (+0.051 million tonnes due to the resources updating; the deposit abandoned), Mosina II (0.029 million tonnes as a result of recalculation) and Długa Goślina (-0.022 million tonnes, the resources crossed out from “The balance…”).

Długa Goślina deposit was crossed out from “The balance…” due to the fact that chalk was co-occurring raw material and has never been exploited. The main raw material – peat – was depleted and the mine was closed down.

There were the verifications of resources elaborated for: Rajgród deposit (+0.028 million tonnes, gyttja resources were documented) and Pomorsko II (+0.110 million tonnes, the rectification of the mistake made in the decision approving the documentation). Moreover, there were also recources of Pęczerzyno-Rynowo deposit updated during the mine management plan elaboration (+0.041 million tonnes).

In 2015, production of chalk increased by 0.027 million tonnes (19%) to the level of 0.172 million tonnes (table 2). The majority of the output constitutes writing chalk production that amounted to 0.155 million tonnes (90%). It is being exploited from 7 deposits (6 in Mazowieckie Voivodeship and 1 in Podlaskie Voivodeship). The remaining part of the production is lacustrine chalk output – it amounted to 0.017 million tonnes (10%). The writing chalk production increased significantly (by 0.028 million tonnes – 22%) while production of lacustrine chalk decreased by 0.6 thousand tonnes (3%). This chalk has been exploited from 2 deposits – Lubiatowo III in Zachodniopomorskie Voivodeship and Roszczyce II in Pomorskie Voivodeship.

Lucastrine chalk occur as co-occurring raw material in brown coal deposit Bełchatów – pole Szczerców and is being temporarily exploited from this deposit (the resources of the chalk are not officially calculated). The output was not carried out in 2015.

Economic resources of chalk in 2015 documented for 7 deposits amounted to 4.35 million tonnes which accounts for 84.5% of anticipated economic resources.

The figure given below shows changes in domestic resources and production of chalk in Poland in the years 1989-2015.

Table 2. List of chalk deposits - thousand tonnes

Prepared by: Wojciech Szczygielski