Carraramarmor

Carraramarmor (efter den norditalienska staden Carrara) är en metamorf produkt av en sedimentär kalksten från triasperioden som bildades i samband med att Apenninerna formades. Den är en av världens mest kända typer av marmor som oftast är vit eller ibland blågrå. Carraramarmor bryts i Carrara i den italienska provinsen Massa and Carrara i Lunigiana, den nordligaste delen av Toscana

Ren utan orenheter/mineraler

Marble is considered a metamorphic rock of carbonatic composition: this means that an already existing rock, of a carbonatic nature, undergoes transformations that make it marble. The rock of origin of the marble is usually sedimentary, and mostly of calcareous composition: the deposition of these sediments takes place in the marine environment, at not excessive depht, because otherwise the calcium carbonate would melt and would not deposit to form limestones.

These are sediments often rich in fossils, whose shapes are then recognizable in some marbles. The deposited material is buried under new sediments and the diagenesis process begins: a complex of chemical and physical processes that convert the dissolved sediment into solid rock. Through cohesion, compaction, redistribution and recrystallization of substances and cementation, the lithification can be reached in variable times: it can take place immediately after deposition or after millions of years.

Once formed, the sedimentary rock begins to travel: the earth's crust is in continuous evolution, and its parts, the so-called plaques, move colliding, creating the geological geometries on which we live. The rocks undergo deepening, elevations, very complex bends that transform them: in our case sedimentary rocks undergo a process called regional metamorphism. A regional metamorphic process involves a significant volume of material which, subjected to high pressures and temperatures, changes its physiognomy and composition, depending on the source material, the duration and intensity of these processes. The sedimentary rock thus meets a transformation that leads to the recrystallization of calcium carbonate with disappearance of fossil remains and formation of crystalline calcite.

The marble is almost formed but it is not yet in its final position: the movements in the earth's crust bring the marble on the surface, or near it, ready to be extracted. It is very difficult to recognize the sedimentary rock of origin of every marble: this is because the metamorphic transformations are very intense and extensive, and because the processes can be multiple and, adding to one another, make the reconstruction of the "path" more and more difficult. of the rock. Making examples is useless as well as disadvantageous: however, we can remember that the final composition can be very varied, depending on the different impurities present, which make each marble unique and inimitable: in fact, the name is taken from the locality of origin or color characteristics or zonatora of the marble itself. The term is also used improperly for non-metamorphic limestone rocks but equally compact and susceptible to processing. Also the appearance is very different: the weaving (the whole of the shape, the size and the arrangement of the granules of the minerals that compose it) and the structure (the set of characters observable on a large scale) give each marble its own peculiarities and unique.