Granite is one of the most abundant rocks on the earth's surface; it is a felsic intrusive igneous rock, made up mostly of feldspar, quartz and micas.

Its name derives from the Latin granum (a grains), with clear reference to its granular or phaneritic texture. Granite is an intrusive igneous rock, it was therefore formed as a result of the slow solidification of a magma that intruded at depths between 1.5 and 50 km.
Granite is split only in small dimensions because it is a hard rock, without stratifications, therefore it is normally cut. This operation can be carried out using traditional blade and grit looms or using the most modern multi-wire machines with diamond wires.
It is usually used as a stone for borders, paving stones, masonry or, in small slabs, for flooring.


Marble is a metamorphic rock composed mainly of calcium carbonate (CaCO3). Marble is formed through a metamorphic process from sedimentary rocks, such as limestone or dolomite, which causes a complete recrystallization of the calcium carbonate of which they are mainly composed and gives rise to a mosaic of calcite or dolomite crystals (mineral) . The combined action of temperature and pressure, during the transformation of the sedimentary rock into marble, leads to the progressive obliteration of the structures and textures originally present in the rock, with the consequent destruction of any fossil, stratification or other sedimentary structure present in the original rock.

The color of the marble depends on the presence of mineral impurities (clay, silt, sand, iron oxides, flint nodules), existing in granules or in layers within the original sedimentary rock. During the metamorphic process these impurities are displaced and recrystallized due to pressure and heat. White marbles are the result of the metamorphosis of limestone free from impurities.
The low refractive index of calcite, which allows light to "penetrate" the surface of the stone before being reflected, gives this material (and especially the white marbles) a special brightness, which has made it particularly appreciated for sculpture. As an example, remember that the artist and sculptor Michelangelo Buonarroti preferred the "white marble" of Carrara for his works.


The name of onyx indicates two completely different types of rocks: siliceous onyx normally black in color streaked with white with SiO2 composition. n H2O, similar to chalcedony (but not quartz, which is crystalline), found in Brazil, Mexico, and other places; and the calcareous onyx, also called "alabastrite onyx", "etoca onyx" or "Egyptian onyx", which is composed of CaCO3 (the one from Montaione is brown or light green that of Pakistan).

Mineralogically it is a variety of chalcedony, that is quartz in compact microcrystalline masses, of an opaque or semi-opaque, uniform color, covering red-brown tones and the entire range of grays up to black.
Like all varieties of quartz it is very hard (6 to 7 on the Mohs scale).
It is formed mainly in a low-temperature and metamorphic phylonian-hydrothermal environment, or, secondarily, in sedimentary rocks where it occurs in massive and stratified form taking the name of flint, a material widely used by man in prehistory and antiquity for the preparation of sharp objects and jewelry.


Quartzite is a type of metamorphic rock composed mainly of quartz. It derives from the dismantling and subsequent metamorphic passage of quartzarenite.

The more colorless, transparent varieties are composed almost exclusively of quartz. Quartz can be associated with other minerals such as micas, potassium feldspar, plagioclases, carbonates, etc. Given the great stability of quartz (a mineral that cannot be easily altered), the information on the metamorphic degree of quartzite is given precisely by the accessory minerals possibly contained in the quartzite. The texture is mainly massive, but the presence of micas can transform it into schistose.
Flint, a sedimentary rock composed almost exclusively of silica, should not be confused with quartzite.
For its excellent mechanical capabilities and resistance to atmospheric agents it is used in construction; It is used for its high silica content as a raw material in the refractory and ceramic industry, as well as in the glass production industry.


Travertine is a light, yellowish rock. The small cavities present in the semi-compact structure are typical of travertine.

The difference between the spongy type limestone deposit and the travertine bank is substantially due to the geological conformation of the formation soil: limestone is one of the most frequent deposits in nature, being produced by the precipitation of calcium carbonate dissolved in water.
A subaerial continental environment in which the calcareous solution has had time to stagnate and settle in a flat territory, close enough to the surface to be able to pass through cycles of emergence and submersion, little disturbed by spring or current waters, favors the formation of travertine.
The color of the travertine depends on the oxides it has incorporated (which happens quite easily, being by nature a fairly porous stone). The natural color varies from milky white to walnut, through various shades from yellow to dark brown. It is common to come across fossil footprints of animals and plants.





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