The origin of natural stone is extremely interesting. Countless elements were mixed and shaped by nature, transformed by heat and pressure into something unique. Three general stone categories are recognized according to their mode of origin: Igneous, Metamorphic and Sedimentary
The Earth’s crust is composed of two general types of stone: Oceanic and Continental. Most, but not all, commercial stone is quarried from continental rock on Earth’s lithosphere - or rocky crust - the cool andrigid outermost rock layer, which varies from about 3 to 25 miles thick. This type of stone is formed by solidification (cooling) or, in some cases, by solid-state transformation of molten or semi-molten material in the Earth’s upper mantle or crust into crystalline rock generally consisting of silicates (compounds with SiO4) and some dark-colored accessory minerals such as iron oxides or other iron - and magnesium-bearing silicate minerals. Though not all igneous stone is volcanic, all genuine granites are solidified slowly from a melt miles deep in the crust, well encapsulated and thus well insulated by surrounding solid rock. This is significant to the quality of granite dimension stone because slow cooling yields the larger crystals that give many commercial granites their distinctive textural character and beauty.
Metamorphic stones are among the most interesting of Earth’s products, for they are the only direct evidence of majorcatastrophic events in the history of the Earth’s crust. Some of this stone is up to 3.8 billion years old, and has changed in its long existence from igneous to sedimentary to metamorphic. Any deeply buried, existing stone– igneous, sedimentary or metamorphic–may be subjected to forces that cause profound mechanical, textural, and ultimately , chemical changes in the mineral content. Metamorphosed stone may or may not resemble its parent stone. Metamorphism is caused by regional-scale crustal movements and mountain-building forces, or by local crustal disturbance, at temperatures about 200oC to near-melting, ≈700-800oC, and pressures from around 450,000 pounds per square inch (psi) to several million psi in the presence of chemically charged aqueous fluids through time. The process produces mechanically deformed stone and chemically alters the mineral assemblages of the parent stone. The new mineral suite may be a different or the same chemical composition as the parent, but as newly formed crystals.
Examples: Marble, Slate, Schist, and Quartzite.
The formation of sedimentary stone is relatively uncomplicated compared to the complex chemistry and natural processes associated with either igneous or metamorphic stone.
Detrital Sedimentary stones are the naturally cemented accumulation of solid granular materials or particles derived from both mechanical and chemical weathering of any existing rock.
Examples: Limestone, Sandstone and Conglomerate.
Chemical Sedimentary stones are the precipitations of chemicals like salt that are the dissolved weathering products of any existing rocks.
Examples: Onyx, Limestone, Dolomite, Travertine and common table salt.
Unlike Natural, these materials are made of crushed stone bound together by resin and petroleum derivative adhesives. A typical resin based material will consist of 93% stone aggregates by weight and 7% resin (66% quartz and 34% resin by volume). Other chemicals may also be added to aid curing, like hydrogen peroxide.
The name of the category is derived from the word describing how these materials are produced; sintering. Sintering is the name of a process through which raw materials in powdered form are transformed into a hard mass of material that has specific characteristics. There are variations of the sintering process and these variations yield a couple of groups under which these materials get placed. Unlike Engineered Stones, Sintered Materials don't have resins or petroleum derivatives on their composition. The two major sub categories of sintered materials are Ceramic Porcelain and Ultracompact Surfaces.
Porcelain is a particular type of ceramic material that is made by Firing, a process of bringing clay and glazes up to a high temperature in two steps: bisque firing and glaze firing. In these processes, unfired ceramic wares are heated to high temperatures in a kiln to permanently set their shapes, vitrify the body and the glaze. Many types of porcelains are fired twice or even three times, to allow decoration using less robust pigments in overglaze enamel.
Like Ceramic Porcelain, these materials are also created using a very unique fabrication process known as Sinterized Particle Tech. This process basically involves the mix of raw elements under high temperatures and extreme pressure.
Exemple: Dekton® , Lapitec®