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aggregation of solid matter composed of one or more of the minerals forming the earth's crust. The scientific study of rocks is called petrology. Rocks are commonly divided, according to their origin, into three major classes—igneous, sedimentary, and metamorphic.
..... Click the link for more information. composed wholly or in large part of calcitecalcite
, very widely distributed mineral, commonly white or colorless, but appearing in a great variety of colors owing to impurities. Chemically it is calcium carbonate, CaCO3, but it frequently contains manganese, iron, or magnesium in place of the calcium.
..... Click the link for more information. or dolomitedolomite
. 1 Mineral, calcium magnesium carbonate, CaMg (CO3)2. It is commonly crystalline and is white, gray, brown, or reddish in color with a vitreous to pearly luster. The magnesium is sometimes replaced in part by iron or manganese.
..... Click the link for more information. crystals, the crystalline texture being the result of metamorphismmetamorphism,
in geology, process of change in the structure, texture, or composition of rocks caused by agents of heat, deforming pressure, shearing stress, hot, chemically active fluids, or a combination of these, acting while the rock being changed remains essentially in the
..... Click the link for more information. of limestonelimestone,
sedimentary rock wholly or in large part composed of calcium carbonate. It is ordinarily white but may be colored by impurities, iron oxide making it brown, yellow, or red and carbon making it blue, black, or gray. The texture varies from coarse to fine.
..... Click the link for more information. by heat and pressure. The term marble is loosely applied to any limestone or dolomite that takes a good polish and is otherwise suitable as a building stone or ornamental stone. Marbles range in color from snow-white to gray and black, many varieties being some shade of red, yellow, pink, green, or buff; the colors, which are caused by the presence of impurities, are frequently arranged in bands or patches and add to the beauty of the stone when it is cut and polished. Marble is used as a material in statuary and monuments, as a facing stone in buildings and residences, and for pillars, colonnades, paneling, wainscoting, and floor tiles. Like all limestones, it is corroded by water and acid fumes and is thus ultimately an uneconomical material for use in exposed places and in large cities. The presence of certain impurities decreases its durability. Marble was extensively used by the ancient Greeks; the Parthenon and other famous buildings were constructed of white Pentelic marble from Mt. Pentelicus in Attica, and the finest statues, e.g., the Venus de' Medici, from the remarkably lustrous Parian marble from Paros in the Cyclades. These same quarries were later used by the Romans. Among the famous marbles of Italy are the Carrara and Siena marbles of Tuscany, which were used by the Romans and the Italian sculptors of the Renaissance. Marbles are quarried in all parts of the world. The finest marbles in the United States come from Vermont, which produces large quantities. Other states important as marble producers are Massachusetts, Maryland, Tennessee, Alabama, Georgia, Missouri, California, Colorado, and Arizona. See alabasteralabaster,
fine-grained, massive, translucent variety of gypsum, a hydrous calcium sulfate. It is pure white or streaked with reddish brown. Alabaster, like all other forms of gypsum, forms by the evaporation of bedded deposits that are precipitated mainly from evaporating
..... Click the link for more information. .
a crystalline rock formed as a result of the recrystallization of limestone or dolomite. The term “marble” is applied commercially to any metamorphic rock of medium hardness that can be polished; this category of rock includes marble, marmorized limestone, dense dolomite, ophicalcite, calcareous breccia, and calcareous conglomerates. Marble almost always contains impurities of other minerals (quartz, chalcedony, hematite, pyrite, limonite, chlorite), as well as organic compounds. The impurities have a varying effect on the quality of the marble, increasing or decreasing its decorativeness.
Marble has a specific gravity of 2.65–2.90 and a compressive strength ranging from 50 to 250 meganewtons per square meter (500–2, 500 kilograms-force per square meter). The abradability is from 0.40 to 3.20 g/cm2, and the water absorption is from 0.15 to 0.50 percent. Finely crystalline marble with dentate bounding of the grains is the most durable and takes the best polish. Structurally uniform marbles are frost resistant.
The color of the marble depends on the impurities. The majority of colored marbles have mottled coloration; the pattern is determined not only by the structure of the marble but also by the direction along which the rock is cut. The color and pattern of the marble appear after polishing. To determine the industrial value of marble deposits, the proximity of transport facilities and the thickness of the overlying stratum of weathered marble (the maximum is usually 5–8 m) are taken into consideration.
Marble is quarried and, less frequently, mined. To obtain monolithic blocks, stonecutting machines and cable saws are used, as are wedges in bored holes and percussive cutters.
Marble has been used since antiquity in architecture as a structural element and as facing owing to its plastic and decorative properties (hardness, fine grain). Marble’s fine grain makes the rock easy to work with and capable of being polished. Polishing reveals the tonal richness of marble and the beauty of its uniform, patchy, or laminated structure. Marble has been used for making mosaics (the incrustation style and Florentine mosaics), reliefs, and freestanding sculptures (primarily carved from marble of a single color—usually white). The relative transparency of the rock results in the delicate play of light and shadow on the surface of marble scupltures.
In the USSR there are as many as 60 known deposits of marble and marmorized limestone (in Karelia, the Ukraine, the Urals, Transcaucasia, Middle Asia, Siberia, and the Far East). The marble reserves in the USSR are virtually inexhaustible. The best grades of white marble from Soviet deposits are used for sculpturing. Marble deposits in Italy include those in Carrara, which yield the finest marble for sculpturing; this marble is white, brilliant, and easy to polish. The Paros quarry in Greece yields the yellowish marble that was used by ancient Greek sculptors. Other countries with marble deposits include Cuba, France, Norway, and the United States.
REFERENCESMetrofanov, G. K. , and I. A. Shpanov. Oblitsovochnye i podelochnye kamni SSSR. Moscow, 1970.
Herbeck, A. Der Marmor. Berlin, 1953.
M. A. LIPSON