Mag­ne­sium ores are an impor­tant min­er­al resource used for the pro­duc­tion of one of the most valu­able light­weight met­als. The prin­ci­pal sources include car­bon­ate min­er­als (dolomite and mag­ne­site), evap­or­ite min­er­als (car­nal­lite and bischof­ite), as well as nat­ur­al brines and sea­wa­ter. Deposits form in both plat­form and fold­ed geostruc­tures and span a wide geo­log­i­cal age range — from the Cam­bri­an to the present day. In indus­try, mag­ne­sium is strate­gi­cal­ly impor­tant due to its physic­o­chem­i­cal prop­er­ties and its broad range of appli­ca­tions.

Mag­ne­sium ores are 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 non-fer­rous met­al ores.

Genetic and geological-industrial types of deposits

The most impor­tant types of mag­ne­sium ores are magnesium–potassium salts formed as a result of leach­ing by ground­wa­ter. This process leads to the for­ma­tion of nat­ur­al brines and saline springs. Sig­nif­i­cant impor­tance is also attrib­uted to dolomite deposits with­in sed­i­men­ta­ry sequences and to mag­ne­site deposits formed through meta­so­mat­ic replace­ment of lime­stones and dolomites by mag­ne­sium-rich solu­tions.

Mod­ern salt deposits form in envi­ron­ments such as enclosed marine bays, lagoons, estu­ar­ies, and intra­con­ti­nen­tal basins. Sea­wa­ter is also an impor­tant source of mag­ne­sium, con­tain­ing approx­i­mate­ly 4% Mg in its dry residue.

Deposits of mag­ne­sium-bear­ing raw mate­ri­als are gen­er­al­ly asso­ci­at­ed with plat­form regions char­ac­ter­ized by long-term sub­si­dence of the Earth’s crust, includ­ing fore­deep basins, syneclis­es, and inter­nal depres­sions. These deposits formed over a broad geochrono­log­i­cal inter­val rang­ing from the Cam­bri­an to the Qua­ter­nary peri­od.

Among the genet­ic types, exo­genic deposits pre­dom­i­nate, includ­ing sed­i­men­ta­ry, sed­i­men­ta­ry-dia­ge­net­ic, and infil­tra­tion deposits. Endo­genic types include hydrother­mal and meta­so­mat­ic deposits.

The most eco­nom­i­cal­ly sig­nif­i­cant mag­ne­sium deposits are asso­ci­at­ed with halogen–evaporite for­ma­tions. These con­sist pre­dom­i­nant­ly of mag­ne­sium chlo­rides and sul­fates, such as car­nal­lite, bischof­ite, and kieserite, occur­ring togeth­er with sodi­um, potas­si­um, cal­ci­um, and boron salts.

Marine and con­ti­nen­tal for­ma­tions are dis­tin­guished, with either com­plete (potash-bear­ing) or incom­plete pro­files. Deposits are also clas­si­fied as fos­sil or mod­ern, depend­ing on their geo­log­i­cal age of for­ma­tion.

Fos­sil salt deposits

Deposits of ancient ori­gin typ­i­cal­ly exhib­it bed­ded, lentic­u­lar, or dome-shaped mor­phol­o­gy. They occur at depths rang­ing from tens to hun­dreds of meters, while salt-bear­ing stra­ta may reach thick­ness­es of 500‑1000 m or more. The largest among them include:

• Verkhnyokam­sk basin (Perm, Rus­sia)
• Pripy­at basin (Belarus)
• Slav­ic-Artemiv deposit (Ukraine)
• Saskatchewan Basin (Cana­da)
• Stas­furt deposit (Ger­many)
• Deposits in the south­ern Unit­ed States

Mod­ern salt deposits

Mod­ern deposits form under evap­o­ra­tion con­di­tions in hot and arid cli­mates. They con­sist of sol­id evap­or­ite salts and brines with salt con­cen­tra­tions exceed­ing 3.5%. Marine deposits include:

• Kara-Bogaz-Gol (Caspi­an Sea)
• Sivash, Donu­zlav, Sasyk (Azov-Black Sea coast)

Con­ti­nen­tal deposits include:

• Lakes Elton, Baskun­chak, Sarpin­sky (RF)
• Great salt lake (USA)

Hydrother­mal mag­ne­site deposits

In deposits of this type, mag­ne­site forms through the replace­ment of dolomites and lime­stones by mag­ne­sium-rich hydrother­mal solu­tions. Ore bod­ies com­mon­ly exhib­it bed­ded, lentic­u­lar, or stock-shaped mor­phol­o­gy, extend­ing for 1–2 km and reach­ing thick­ness­es exceed­ing 500 m. Well-known exam­ples include:

• Triben, Raden­thein (Aus­tria)
• Satkin group of deposits (Ural, Russ­ian Fed­er­a­tion)
• Savinske, Onatske (Irkut­sk region)

Infil­tra­tion deposits

These deposits form as a result of lat­erit­ic weath­er­ing of ser­pen­tinized ultra­maf­ic rocks. Mag­ne­sium migrates into the low­er hori­zons of the weath­er­ing crust, where it pre­cip­i­tates as MgCO₃ gel. Ore bod­ies occur as nests, lens­es, veins, and stock­works. The ore-bear­ing zone usu­al­ly has a thick­ness of 10–15 m, some­times reach­ing 30–40 m.

Such deposits are known in: Cuba, New Cale­do­nia, Kaza­khstan, Cau­ca­sus, Khalilovskoye.

Ukraine’s mag­ne­sium indus­try ful­ly meets domes­tic demand for metal­lic mag­ne­sium due to the pres­ence of potassium–magnesium salt deposits of sul­fate and sulfate–chloride com­po­si­tion. An addi­tion­al impor­tant source of raw mate­r­i­al is also the brine of salt lakes and bays in Crimea.

The main mag­ne­sium-bear­ing min­er­als include car­nal­lite, lang­bei­nite, kai­nite, bischof­ite, kieserite, poly­halite, and epsomite. The largest pro­duc­tion is con­cen­trat­ed at the Kalush Chem­i­cal and Met­al­lur­gi­cal Plant and the Zapor­izhzhia Tita­ni­um and Mag­ne­sium Plant. A sig­nif­i­cant share of mag­ne­sium is export­ed, main­ly to Rus­sia.

• The Pre­carpathi­an potash basin, includ­ing the Kalush–Holynske and Steb­nyk deposits. Here, salts are pre­dom­i­nant­ly of sul­fate com­po­si­tion and are com­plex in nature. Extrac­tion can be car­ried out both by under­ground and open-pit min­ing meth­ods.
• In the Donet­sk region, bischof­ite hori­zons have been iden­ti­fied in deep bore­holes, par­tic­u­lar­ly at the Zatu­ryne and Novopodilne deposits. Extrac­tion is per­formed by in-situ solu­tion min­ing (well leach­ing).
• In Crimea, the brines of the Syvash lagoon, as well as Lake Stare and Lake Sasyk, con­tain up to 1.15% MgO and serve as sources of chloride–sulfate mag­ne­sium salts.

Promis­ing non-tra­di­tion­al types of mag­ne­sium raw mate­ri­als include meta­mor­phic mag­ne­site and talc–magnesite deposits, high-mag­ne­sium meta-ultra­ba­sic rocks, and dolomitic mar­bles.

The Pryvydne deposit con­tains over 100 mil­lion tons of ore with a high MgO con­tent (up to 41%). This raw mate­r­i­al is suit­able for the pro­duc­tion of refrac­to­ries, fer­til­iz­ers, and cement.

The Veselianske deposit has reserves of about 1,322 thou­sand tons and a poten­tial of up to 250 mil­lion tons.

In the Azov region crys­talline mas­sif, numer­ous meta-ultra­ba­sic bod­ies have been iden­ti­fied, which may also be used as addi­tives in refrac­to­ry mate­ri­als.

Mag­ne­sium ores are an impor­tant resource for the met­al­lur­gy, aero­space, and chem­i­cal indus­tries. Their acces­si­bil­i­ty, diver­si­ty of genet­ic types, and effi­cient extrac­tion tech­nolo­gies ensure a sta­ble sup­ply of mag­ne­sium for strate­gi­cal­ly impor­tant sec­tors. Con­sid­er­a­tion of geo­log­i­cal con­di­tions, ore-body mor­phol­o­gy, and the chem­i­cal com­po­si­tion of raw mate­ri­als allows for the opti­miza­tion of min­ing process­es and the reduc­tion of envi­ron­men­tal impact.