the basics of natural stone selection

Natural stones on the basis of formation

Generally and in geological terms, natural stones are classified into three sedimentary, igneous and metamorphic stones. The sedimentary stones are resulted by the deposition of the sediments and sea creatures in the depths of the aqueous media including the seas and the oceans under the effect of high levels of pressures and temperatures during long geological periods of time. On the other hand, the igneous stones are the product of cooling down of the lava inside or outside on the surface of the Earth, making up the intrusive and extrusive igneous stones respectively. In addition, the metamorphic stones are the product of pressure and temporal enforcements on either types of sedimentary and igneous resulting in recrystallization inside the fabric of the stones.

Natural stone selection according to the application

According to the definitions, standards and the recommendations made by the Marble Institute of America (MIA), the type of natural stone is of high significance in right selections. For example, igneous stones are harder and have higher index of Moh's hardness due to the more compact structures they consist of. This is why Granite as an igneous stone is one of the best natural stone types for the environments that need high abrasive and mechanical strengths. On the other hand, Marble as a metamorphic stone is not a proper type of stone for the environments that are in close contact with the acidic materials. It is because of the fact that Marble is mainly comprised of Calcite which is highly reactive to the acids and gets fizzing form by the erosion.

What is the link between the stone finish and the applications?

According to the established standards and engineering recommendations, the stone finish has a high impact on where to install the natural stones. For instance, Marble with a honed finish instead of polished finish will resist more stronger against the traffic loads. This is due to the fact that the impacts of heavy traffic including etching and scratching are less visible in the honed matt finish.

Mechanical parameters of natural stones based on the applications

For exterior applications, the natural stones should have high resistance against fracturing, weathering, slipping, reactions with acids, erosion, efflorescence, thermal expansion and contraction, freezing-thawing cycle and so on. In this way, the natural stone will be showing high durability against the damaging elements of the environment. This is performed by the right type of the natural stone in addition to the appropriate stone finish . That is why Marble and Limestone are not proper options for the exterior applications whereas Travertine is a great and suitable option as a facing stone by virtue of its relatively low density and high durability.