Technical characteristics of stones (chemical composition of stones)

Rocks are tested for their chemical composition to determine their constituent elements. Knowing the composition of the stone will help to identify the stone, cutting, polishing, polluting materials, the effect of the ambient air on them and the effect of the stored and consumed materials next to them. The presence of free silica in limestone creates problems in cutting and polishing the stone, which will be indicated by the chemical composition of the stone.

Chemical analysis of rocks along with their microscopic examination can be useful to identify minerals and percentage of elements. At the same time, chemical decomposition alone is not enough and does not show the presence of harmful elements. The chemical analysis of igneous rocks shows the percentage of silicon oxide, aluminum oxide and different percentages of iron oxides, calcium, magnesium and alkalis, which depends on the type of rock. If the limestones are pure, they only contain calcium carbonate and magnesium calcium carbonate, but if they contain clay impurities, they also contain some silicon oxide, aluminum oxide, iron oxide and some chemical water.

In the case of purity, sandstones do not have other oxides except silicon oxide, but if they are present, they also contain aluminum oxide, iron oxide, and some amounts of chemical water. If they are carbonate clay, they may also show some percentage of lime.

Today, microscopic tests are very important for studying rocks, which can be used to study the following things.

• Construction

• texture, degree of crystallization, size and shape of grains, relationship between crystals

• The type and percentage of constituent minerals and how they are distributed

• Detection of harmful minerals

• Determining the direction of minerals

• Determining the degree of alteration of minerals and the type of altered minerals

• Degree of weathering

• – Porosity percentage in sedimentary rocks

• Determining the type of paste and cement of sedimentary rocks

• Types of joints and investigation of the pressures on the rock from a tectonic point of view

• Color grade

In general, in the case of granite stones, it is necessary to know the water absorption coefficient, apparent specific gravity, tensile stress, compressive and dry stress, abrasion strength (friction), modulus of elasticity, determining the types of constituent crystals and their construction. In the case of limestone, it is also necessary to determine the water absorption coefficient, specific gravity, tensile stress, compressive and dry stress, and abrasion strength. For calcite, dolomite, serpentine and travertine, water absorption coefficient, specific gravity, tensile stress, compressive and dry stress, abrasion strength (friction) and determination of binding mortar (for sandstone) are required.

From the point of view of mining, some features of rocks are of special importance for choosing the extraction method, drilling method, type of explosive, shape and type of drill head and type of machinery, the most important of which are: modulus of elasticity, Poisson’s ratio, rock hardness, crushing, abrasion and Water absorption capacity of stone. The strength and stability of rocks are very important physical and chemical properties of minerals and rocks that determine the mining method and the system of using these methods.