as a general information, one of the most interesting facts about Marble stone with granular texture like limestone or dolomite (i.e. a rock composed of calcium-magnesium carbonate) is that it has been restored under the influence of heat, pressure and aqueous solution.
marble stone texture high resolution
Commercially, it contains all decorative calcium-rich stones that can be polished, as well as some serpentines (word antiquities).
Petrographically, marble is massive rather than thin layered and consists of a mosaic of calcite grains that rarely show any trace of crystalline form under the microscope.
They are crossed by microcracks corresponding to rhombohedral cleavages of calcite.
In the more deformed rocks the grains show grooves and are elongated or crushed in certain directions.
Marble Stone Texture features
Marble is often interbodied with metamorphic rocks such as mica schists, phyllites, gneisses, and granulites, and occurs most frequently in older layers of the earth's crust deeply embedded in regions of high folding and igneous intrusion.
Occasionally, as in Carrara, Italy, and Bergen, Norway, rock restoration has not completely destroyed the organic structures.
Most of the white and gray marbles from Alabama, Georgia, western New England, Yule, and Colorado are reclaimed stones, as are a number of famous Greek and Italian statuary marbles from antiquity still excavated Among these.
Parian marble, Pantelic marble from Attica in which Phidias , Praxiteles and other Greek sculptures made their major works, and the snow-white Carrara marble used by Michelangelo and Antonio.
Marble Stone Texture advantages
Canova and favored by modern sculptors The National Gallery of Art in Washington has an exterior of Tennessee marble , and the Lincoln Memorial has marble from Yule, Colorado, Alabama (roof transparencies), and Georgia (Lincoln statue).
Even the purest metamorphic marbles, such as Carrara, contain some accessory minerals, which in many cases make up a considerable part of the mass Quartz is most common in small spherical grains, colorless or pale yellow mica (muscovite and phlogopite), dark lustrous fragments of graphite, iron oxide and small crystals of pyrite Many marbles are other minerals, usually silicates of lime or magnesia.
Diopside is often visible and can be white or light green; White banded tremolite and light-green actinolite also occur; The feldspars encountered may be potassium but are often plagioclase (sodium-rich calcium) such as albite, labradorite.
anorite or scapolite, various types of garnet, vesuvianite, spinel, forsterite, perichlase, brucite, talc, zoisite, wollastonite, chlorite , tourmaline, epidote, chondrodite, biotite, titanite and apatite are all potential accessory minerals.
Pyrrhotite, sphalerite, and chalcopyrite may occur in small amounts.
These minerals represent impurities in the original limestone, which react during metamorphism to form new compounds.
Alumina represents a mixture of clays; The silicates get their silica from quartz and clays; The original sedimentary rock contains iron from limonite, hematite or pyrite.
In some cases it is possible to trace the original beds of calcareous sediments by mineral bands in the marble.
Silicate minerals, if present in any significant quantity, can color marble; For example, green in the case of green pyroxene and amphibole; brown in garnet and vesuvianite; and yellow in epidote, chondrodite and titanite.
The black and gray colors result from the presence of fine scales of graphite.
Flakes of calcium-silicate rock alternate or form nodules and bands with flakes of marble, sometimes producing interesting decorative effects, but these rocks are particularly difficult to finish because of the large difference in hardness between silicate and carbonate minerals.
Marble Stone Texture conclusion
Subsequent physical deformation and chemical decomposition of metamorphic marbles often produce attractive colors and varieties.
Decomposition gives hematite, brown limonite, pale-green talc, and especially, ophichalcite or ward characterize the antiquities, the derivatives of forsterite and diopside become green.
or yellow snakes Earth movements can fracture rocks, producing fissures that are later filled with calcite veins; Thus a beautifully bricked or veined marble is formed.
Sometimes broken pieces are bent into spheres by the marble flow under pressure.
