A coating having a thickness between 0.1 and 2 mm is obtained from a mixture with the following composition: 10-25% by weight of micronized powder; 40-60% by weight of inorganic gravels of petrographic origin of sizes comprised between 0.063 - 2 mm; 10-40% by weight of a polymerisable base resin selected from polyurethane, polyester, epoxy or acrylic, with additives; and optionally pigments. The proportion of the mentioned gravel and micronized powder of the coating is up to 90% in an inner most area of interphase between coating and surface of the petrous substrate, covering one third of the thickness of the coating. The method comprises depositing the mentioned mixture on the substrate and vibrating the assembly, and subsequently proceeding to a step of curing and subsequent mechanical finishing of the surface.