Argillite. Char­ac­ter­is­tics, dis­tri­b­u­tion, and appli­ca­tion

Argillite is a sed­i­men­ta­ry rocky clayey rock formed as a result of com­paction, dehy­dra­tion, and cemen­ta­tion of clays dur­ing dia­ge­n­e­sis and epi­ge­n­e­sis. Its name comes from the Greek words “ἄργιλος” (clay) and “λίϑος” (stone), which empha­sizes its clayey ori­gin and stony struc­ture.

Argillite is includ­ed in the list of min­er­als of nation­al impor­tance approved by Res­o­lu­tion of the Cab­i­net of Min­is­ters of Ukraine No. 827 of Decem­ber 12, 1994, as raw mate­r­i­al for petro­le­um and brick and tile pro­duc­tion.

Physical and chemical properties

Argillite is a rock com­posed of fine­ly dis­persed clay mate­r­i­al, pre­dom­i­nant­ly mont­mo­ril­lonite and hydromi­ca. It con­tains impu­ri­ties of iron hydrox­ides, glau­conite, sil­i­ca, as well as relict min­er­als such as quartz, feldspars, mus­covite, biotite, chlo­rite, and some­times zir­con, rutile, and tour­ma­line. The con­tent of clas­to­genic mate­r­i­al in the rock is low and does not exceed 5% of the total vol­ume.

The main dif­fer­ence between argillite and ordi­nary clays is its increased den­si­ty and resis­tance to soak­ing. Unlike clay shales, it is char­ac­ter­ized by less pro­nounced lay­er­ing. These fea­tures make argillite an impor­tant mate­r­i­al for var­i­ous indus­tri­al appli­ca­tions.

Distribution in Ukraine

In Ukraine, argillite deposits and raw mate­ri­als for expand­ed clay are wide­spread in all regions and are asso­ci­at­ed with deposits of var­i­ous geo­log­i­cal sys­tems, such as Car­bonif­er­ous, Per­mi­an, Juras­sic, Neo­gene, Pale­o­gene, and Qua­ter­nary. The most famous deposits of expand­ed clay raw mate­ri­als are con­cen­trat­ed in Don­bas, Moun­tain Crimea, the Carpathi­ans, and the Lviv-Volyn basin.

Among the explored deposits includ­ed in the State Fund of Min­er­al Deposits of Ukraine, there are 55 deposits of expand­ed clay raw mate­ri­als. Of these, only 5 are ready for exploita­tion, and only 2 are active­ly being devel­oped — the Snizhne deposit in the Donet­sk region and the Novoz­vanivske deposit in the Luhan­sk region.

The Snizhne deposit, locat­ed near the city of Snizhne in the Donet­sk region , has total reserves of argillites and silt­stones esti­mat­ed at 3,492 thou­sand m³. The main pro­duc­tive lay­er is rep­re­sent­ed by 9 m thick argillites cov­ered by lay­ers of silt­stones and sandy clays. The deposit is oper­at­ed by the Snizhne expand­ed clay grav­el plant.

The Novoz­vanivske deposit in Luhan­sk region has an area of 27.4 hectares and con­sists of alter­nat­ing lay­ers of argillites (70–80%) and silt­stones (20–30%), form­ing a thick­ness of 24.3 to 69 m. The total proven reserves of this deposit are esti­mat­ed at 12,818 thou­sand m³, and it is promis­ing for the pro­duc­tion of expand­ed clay.

The Goly­atyn deposit of var­ie­gat­ed Upper Cre­ta­ceous argillites is locat­ed in Zakarpat­tia Oblast, north of the vil­lage of Goly­atyn on the right bank of the Goly­atyn­ka Riv­er. The argillites are hydromi­ca. The raw mate­r­i­al is low-melt­ing with an aver­age sin­ter­ing tem­per­a­ture and refrac­tori­ness index of 1200–1300°C.

In addi­tion, the fol­low­ing deposits are locat­ed in the Donet­sk region: Vesela Doly­na, Kostyan­tynivske (Piv­den­na sec­tion), Pro­le­tarsk, Staromykhailivske, Skhid­nokhartske, Fenol­nyanske (Fenol­nyan­s­ka and Shy­ro­ka Bal­ka sec­tions). The Luhan­sk region has the Kov­pakivske, Lutuhinske, Mar­murove (Novopavlivske), and Nyzh­no­holchynske deposits. Despite the avail­able reserves of raw mate­ri­als, none of these deposits are cur­rent­ly being devel­oped.

Use of argillite

Due to its unique phys­i­cal and chem­i­cal prop­er­ties, argillite plays an impor­tant role in indus­try, pro­vid­ing raw mate­ri­als for the man­u­fac­ture of var­i­ous build­ing mate­ri­als and prod­ucts. Its use cov­ers sev­er­al key areas.

One of the main areas of appli­ca­tion for argillite is the pro­duc­tion of expand­ed clay. This mate­r­i­al is obtained by heat­ing argillite to tem­per­a­tures of 1050–1250 °C. Dur­ing the heat­ing process, argillite expands, form­ing a light and porous filler. Expand­ed clay is used in con­struc­tion to pro­duce light­weight con­crete that com­bines low weight, high strength, and ther­mal insu­la­tion prop­er­ties. In addi­tion, expand­ed clay is used as a ther­mal insu­la­tion mate­r­i­al, a filler for soils in agri­cul­ture, and in land­scape design.

Argillite is an impor­tant com­po­nent in cement pro­duc­tion because it con­tains large amounts of sil­i­ca and alu­mi­na, which are nec­es­sary for the for­ma­tion of clink­er, the basis of cement. Its use improves the phys­i­cal and mechan­i­cal prop­er­ties of cement and reduces the cost of pro­duc­tion.

Kaolin argillites, which have a high con­tent of alu­minum oxides, are known as “flint clay.” They are used in the pro­duc­tion of refrac­to­ry mate­ri­als that can with­stand high tem­per­a­tures and aggres­sive chem­i­cal envi­ron­ments. Such mate­ri­als are used in met­al­lur­gy, the glass indus­try, and ener­gy to man­u­fac­ture fur­nace lin­ings and ther­mal insu­la­tion blocks.

In addi­tion, due to its ther­mal insu­la­tion prop­er­ties, argillite serves as the basis for the man­u­fac­ture of insu­la­tion boards and blocks used in con­struc­tion to insu­late build­ings and struc­tures.

In agri­cul­ture, argillite is used as a com­po­nent to improve soil struc­ture. Due to its abil­i­ty to retain mois­ture, it helps to pro­vide favor­able con­di­tions for plant growth. In addi­tion, it is used in the man­u­fac­ture of fer­til­iz­ers and as a filler in the feed indus­try.

Thus, argillite is an impor­tant resource for the con­struc­tion indus­try in Ukraine, and its deposits have sig­nif­i­cant poten­tial for the devel­op­ment of expand­ed clay and oth­er mate­ri­als pro­duc­tion.