Gran­ite. Nat­ur­al beau­ty and strength in one stone

Gran­ites — are coarse-crys­talline igneous plu­ton­ic rocks char­ac­terised by a high con­tent of quartz, feldspar and mica. It is a unique rock that can with­stand heavy loads with­out dam­age, which is why it is wide­ly used in con­struc­tion and sculp­ture.

Gran­ites are includ­ed in the list of min­er­als of nation­al impor­tance approved in Res­o­lu­tion No. 827 of the Cab­i­net of Min­is­ters of Ukraine dat­ed 12 Decem­ber 1994, as raw mate­ri­als for fac­ing mate­ri­als (dec­o­ra­tive stones) and raw mate­ri­als for rub­ble stone.

Mineral composition

Gran­ites are polymin­er­al rocks with an acidic com­po­si­tion. The min­er­al com­po­si­tion of gran­ite can vary, but gen­er­al­ly includes the fol­low­ing main min­er­als:

• Quartz (approx­i­mate­ly 20–40%) is the most com­mon min­er­al in gran­ites.
• Potas­si­um-sodi­um feldspars (approx­i­mate­ly 35–45%) — ortho­clase, micro­cline, etc.
• Pla­gio­clases (approx­i­mate­ly 10–65%) are a group of min­er­als that include albite, oligo­clase, labradorite, etc.
• Biotite and mus­covite are min­er­als belong­ing to the mica group.
• Oth­er min­er­als can also be found in gran­ites, such as amphi­boles, pyrox­enes, and oth­ers. They can add an addi­tion­al vari­ety of colours and tex­tures to gran­ite.

The min­er­al com­po­si­tion of gran­ite can vary depend­ing on the place of its for­ma­tion. For exam­ple, some types of gran­ite may con­tain more biotite than oth­ers, which gives them a dark­er colour. In addi­tion, some types of gran­ite may con­tain oth­er min­er­als, such as gar­net or tour­ma­line, which can affect their colour and tex­ture. The min­er­al com­po­si­tion of gran­ite can also be affect­ed by weath­er­ing and ero­sion, which can change the appear­ance of the rock over time.

Physical properties

The phys­i­cal prop­er­ties of gran­ite depend on its min­er­al com­po­si­tion, struc­ture and the con­di­tions under which it was formed. The main phys­i­cal prop­er­ties of gran­ite range from

Texture and grain size

The tex­ture and grain size are impor­tant char­ac­ter­is­tics of gran­ite and can vary depend­ing on where it is found and the con­di­tions under which it was formed. The tex­ture of gran­ite is usu­al­ly described as coarse-grained and gran­u­lar, which means that it con­sists of vis­i­ble min­er­al grains. The indi­vid­ual min­er­al grains can vary in size and shape, but they are usu­al­ly larg­er than those of oth­er rock types. This coarse-grained tex­ture gives gran­ite its dis­tinc­tive appear­ance and dura­bil­i­ty, mak­ing it a pop­u­lar choice for use in con­struc­tion and build­ing mate­ri­als.

The grain size of gran­ite can vary depend­ing on the con­di­tions under which it was formed. The size of the min­er­al grains in gran­ite is usu­al­ly deter­mined by the rate of cool­ing and solid­i­fi­ca­tion of the mag­ma. If the mag­ma cools slow­ly, the min­er­al grains will be larg­er, and if it cools quick­ly, the min­er­al grains will be small­er. As a result, the grain size of gran­ite can vary from fine-grained to very coarse-grained depend­ing on the cool­ing rate. In addi­tion, the grain size of gran­ite can also affect its prop­er­ties. Coarse-grained vari­eties are gen­er­al­ly more durable and weath­er-resis­tant than fine-grained gran­ite because they have a stronger bond­ing struc­ture. How­ev­er, fine-grained gran­ite can have a smoother tex­ture and is eas­i­er to work with, mak­ing it a pop­u­lar choice for use in dec­o­ra­tive appli­ca­tions such as coun­ter­tops and tiles.

The genesis of granite

Gran­ites are intru­sive (igneous) rocks with an acidic com­po­si­tion (Al2O3 con­tent > 65%), which are formed as a result of mag­ma crys­talli­sa­tion process­es. The gen­e­sis of gran­ites is a long and com­plex process. Ini­tial­ly, gran­ites devel­op through the melt­ing of sil­i­cate-rich rocks under high tem­per­a­ture and pres­sure. This process takes place in the upper man­tle zone or below, at a depth of about 2–50 km. After melt­ing, mag­ma is formed, which has a pre­dom­i­nant­ly alu­mi­na chem­i­cal com­po­si­tion. As it ris­es to the upper lay­ers of the Earth­’s crust, it begins to cool and cer­tain groups of min­er­als grad­u­al­ly form from it — the process of frac­tion­al crys­talli­sa­tion. This is how quartz, feldspar (ortho­clase or micro­cline), mica (mus­covite or biotite) and oth­er min­er­als (pyrox­enes, amphi­boles, gar­nets, tour­ma­line, etc.) are sep­a­rat­ed from the molten mass. After crys­talli­sa­tion, rocks can remain at a con­sid­er­able depth under­ground or be brought to the upper lay­ers of the Earth­’s crust through var­i­ous tec­ton­ic process­es (moun­tain ridge uplift, land­slides, etc.).

It is impor­tant to note that gran­ites can be formed in var­i­ous geo­log­i­cal envi­ron­ments, such as con­ti­nen­tal sub­duc­tion zones, con­ti­nen­tal plat­forms, dur­ing moun­tain for­ma­tion process­es, and even on the seabed.

Granite deposits in Ukraine

Ukraine is rich in gran­ite deposits, the bulk of which are con­cen­trat­ed with­in the Ukrain­ian Crys­tal Shield. Sig­nif­i­cant gran­ite reserves are con­cen­trat­ed in Zhy­to­myr, Kirovohrad, Zapor­izhzhia, Dnipro and Donet­sk regions.

The most pop­u­lar gran­ites are:

• red — Kapustin­sky deposit — in Novoukrain­ka, Kirovo­grad region;
• pink­ish-red, red-yel­low, brown – Did­kovet­sky, Omelyanivsky, Kornin­sky, Liznikovsky deposits in Zhy­to­myr region;
• dark crim­son – Tokivske and Kudashiv­ske fields in Dnipropetro­vsk region;
• grey – Tanske deposit in Cherkasy region, Pokos­tivske deposit in Zhy­to­myr region and Yantsivske deposit in Zapor­izhzhya region, etc.

The undis­put­ed leader in terms of esti­mat­ed reserves is the Korostyshiv deposit in Zhy­to­myr region, which pro­duces both crushed stone and block stones, with total proven reserves of 13 mil­lion m3. Due to their high aes­thet­ics and resis­tance to wear, Korostyshiv gran­ites are high­ly val­ued both in Ukraine (they are used to clad the Khreshchatyk metro sta­tion in Kyiv) and around the world, so a sig­nif­i­cant part of the fin­ished prod­ucts are export­ed.

Requirements for the quality of minerals

The qual­i­ty of gran­ites is reg­u­lat­ed in accor­dance with the “Instruc­tion on the appli­ca­tion of the Clas­si­fi­ca­tion of Min­er­al Reserves and Resources of the State Sub­soil Fund to deposits of build­ing and fac­ing stone.”

Fac­ing stone must meet the require­ments of DSTU B V.2.7–59-97 “Nat­ur­al stone blocks for the pro­duc­tion of fac­ing prod­ucts. Gen­er­al tech­ni­cal con­di­tions”. To eval­u­ate the fac­ing stone, the com­pres­sive strength, frost resis­tance, coef­fi­cient of strength reduc­tion when sat­u­rat­ed with water are lim­it­ed; abra­sion indi­ca­tors, radi­a­tion and hygiene indi­ca­tors of the rock, dimen­sions, vol­ume of fac­ing stone blocks, their shape and sur­face char­ac­ter are reg­u­lat­ed depend­ing on the type of rock. The com­pres­sive strength is deter­mined in a dry and water-sat­u­rat­ed state.

The sawn wall stone must meet the require­ments of GOST 4001–84 ‘Wall stones from rocks. Tech­ni­cal con­di­tions’. This stan­dard lim­its the aver­age den­si­ty, water absorp­tion, coef­fi­cient of reduc­tion of strength when sat­u­rat­ed with water, frost resis­tance, com­pres­sive strength, weight of one stone, dimen­sions and appear­ance. The block of wall stone can­not have lay­ers of clay and marl, as well as vis­i­ble delam­i­na­tions and cracks.

The qual­i­ty of rub­ble stone (crushed stone) is reg­u­lat­ed by DSTU B V.2.7–75-98 “Dense nat­ur­al crushed stone and grav­el for build­ing mate­ri­als, prod­ucts, struc­tures and works. Spec­i­fi­ca­tions”, accord­ing to which, depend­ing on the size, crushed stone is divid­ed into the main frac­tions: 5–10 mm; 10–20 mm; 20–40 mm; 40–80 (70) mm. This stan­dard also stip­u­lates require­ments for strength, frost resis­tance, abra­sion, con­tent of dust and clay par­ti­cles, harm­ful impu­ri­ties, lamel­lar and nee­dle-shaped grains, con­tent of weak rock grains, and con­tent of nat­ur­al radionu­clides.

The frost resis­tance is deter­mined in accor­dance with DSTU B V.2.7–42-97 ‘Meth­ods for deter­min­ing water absorp­tion, den­si­ty and frost resis­tance of build­ing mate­ri­als and prod­ucts’, and abra­sion resis­tance is deter­mined in cas­es where blocks of rock are used to pro­duce floor and stair­case fac­ing mate­ri­als.

Granite mining

The gran­ite extrac­tion process is com­plex and requires spe­cialised knowl­edge and equip­ment. It involves the extrac­tion of rock from quar­ries and its crush­ing and pro­cess­ing for fur­ther use. It is impor­tant to take into account the envi­ron­men­tal aspects of gran­ite min­ing to reduce its impact on the envi­ron­ment and pre­serve the deposits of this min­er­al. The organ­i­sa­tion of gran­ite min­ing is based on a quar­ry devel­op­ment project, which has cer­tain fea­tures and dif­fer­ences, spe­cif­ic to this par­tic­u­lar min­er­al.

Extrac­tion and pro­cess­ing meth­ods should take into account the fol­low­ing aspects:

• Preser­va­tion of nat­ur­al resources and the envi­ron­ment from neg­a­tive impact;
• Pro­duc­tion of prod­ucts of appro­pri­ate qual­i­ty and range;
• Max­imis­ing the effi­cient extrac­tion of stone from the rock mass;
• Preser­va­tion of the nat­ur­al prop­er­ties of the stone dur­ing extrac­tion (for exam­ple, block­i­ness and dec­o­ra­tive­ness);
• Wide­spread use of var­i­ous oppor­tu­ni­ties for pro­cess­ing raw mate­ri­als.

When choos­ing the most appro­pri­ate sys­tem for the devel­op­ment of a nat­ur­al stone deposit, an analy­sis of var­i­ous options for tech­ni­cal and eco­nom­ic approach­es to the devel­op­ment and pro­cess­ing of raw mate­ri­als is car­ried out. The use of high explo­sive mate­ri­als for crush­ing arti­fi­cial stone is not allowed. If the deposit con­sists of het­ero­ge­neous rocks or con­tains dif­fer­ent min­er­als, sep­a­rate areas may be allo­cat­ed for sep­a­rate pro­cess­ing of each type of raw mate­r­i­al. When pro­cess­ing rocks into crushed stone, it is rec­om­mend­ed to use wash­ing meth­ods, as well as dedust­ing and dry­ing of crushed stone. This approach helps to improve prod­uct qual­i­ty and ensure opti­mal use of the mate­r­i­al.

Applications and uses of granite

Thanks to its phys­i­cal prop­er­ties, tex­ture and struc­ture, gran­ite has become a well-known and pop­u­lar mate­r­i­al that can be used in a wide range of appli­ca­tions, both func­tion­al and dec­o­ra­tive. Its dura­bil­i­ty, strength and nat­ur­al beau­ty make it a pop­u­lar choice for many dif­fer­ent indus­tries, from con­struc­tion to art and design. A vari­ety of house­hold prod­ucts are made from gran­ite. Depend­ing on the colour of the gran­ite, mon­u­men­tal pan­els, fur­ni­ture and indi­vid­ual inte­ri­or ele­ments are cre­at­ed. Inte­ri­or cladding with gran­ite is quite com­mon in pub­lic places such as cin­e­mas, muse­ums, sub­ways, libraries and oth­ers. Peo­ple of art active­ly use this mate­r­i­al to cre­ate sculp­tures, mon­u­ments, and ensem­bles, as gran­ite allows you to get fig­ures of exact dimen­sions with the nec­es­sary pro­por­tions and detail, thanks to its pro­cess­ing. Gran­ite is also used to cre­ate exclu­sive exte­ri­ors. It is used to make para­pets, var­i­ous flowerbeds and mon­u­ment foot­ings. For inte­ri­or solu­tions, gran­ite is used to make stairs, columns, balus­ters and even balls of the cor­rect shape.

Gran­ite mate­r­i­al makes any object look ele­gant and reli­able. Its vari­ety of colours and tex­tures allows you to be cre­ative in design­ing and cre­at­ing attrac­tive inte­ri­ors and exte­ri­ors. Gran­ite in the form of slabs with dif­fer­ent tex­tures obtained by pro­cess­ing the front sur­face is used for exte­ri­or cladding of build­ing facades, cre­at­ing lux­u­ri­ous or strict con­cepts.

In addi­tion, gran­ites are the high­est qual­i­ty raw mate­r­i­al for the pro­duc­tion of crushed stone. They con­tain a rel­a­tive­ly small amount of dark-coloured min­er­als that are eas­i­ly released dur­ing crush­ing and sort­ing, are char­ac­terised by high strength, frost resis­tance, and are frag­ile, so they are eas­i­ly crushed and pro­duce a small amount of waste that is resis­tant to weath­er­ing. The most durable and frost-resis­tant are the fine-grained, leu­co­crat­ic vari­eties of gran­ite. Gran­ite crushed stone has many appli­ca­tions: as an aggre­gate for con­crete mass, for the con­struc­tion of motor­ways, rail­way tracks or land­scap­ing.

Thus, gran­ite is an impor­tant mate­r­i­al in con­struc­tion and oth­er indus­tries. Its strength, dura­bil­i­ty and aes­thet­ic prop­er­ties make it indis­pens­able in many projects. The use of gran­ite adds ele­gance and dura­bil­i­ty to exte­ri­or struc­tures and inte­ri­ors. Undoubt­ed­ly, gran­ite is a tru­ly unique rock.