Perlit is a volcanic vitreous argillossilite rock whose operative cause is the acidic lava, which was injected superficially or underwater during volcanic activities. The latter was then cooled and solidified rapidly, under conditions that did not allow the mineral atoms to be placed in crystal lattice formations, which eventually gave perlitus its vitreous form. . 

A very important factor that affected the formation of perlit was the presence of water and various gases trapped in its mass, at the time of its cooling and solidification. The name comes from its texture characterized by the presence of grains, reminiscent of small pearls ( pearls). Petrographic perlitis is a volcanic material. It has a characteristic perlitic structure consisting of concentric fractures that resemble pearls placed throughout the glass, sometimes circularly and sometimes in polygonal formations. 

This is also the intense characteristic of perlitus. The above-mentioned fractures are a phenomenon observed in acidic glasses.

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