Marmomacc 2006

[Huligar]

Marmomacc 2006, the International Exhibition of Marble, Stone and Technology and Building Materials Show, Verona, Italy.

	Marble MARBLE: CHARACTERISTICS This standard includes general information on the characteristics and common uses of marble and identifies typical problems associated with the material. INTRODUCTION Marble is an extremely hard, metamorphic stone composed of calcite (CaCO3). It is formed as a result of the recrystallization of limestone under the intense pressure and heat of geologic processes. The effect of this process is the creation of a stone with a very tight crystalline structure and small but definite porosity. Because of its structure, marble can take a very high polish and is a very popular decorative stone for architectural and sculptural uses. The limited porosity of marble, especially polished marble, makes it less vulnerable to the leaching effects of water. Calcium carbonate, however, of which marble is composed, is highly susceptible to attack by acidic agents. Marble is readily dissolved by acids, even very dilute acids, however the actual results of acidic exposure will vary with the nature of the acid. Chlorides, nitrates, sulfates and other chemical compounds react differently with marble and produce various by-products, which have a wide range of solubility and impact on the durability of marble. For this reason, it is always important to determine the exact type of pollutants causing marble deterioration. Marble itself can be of two types, one composed of calcite and the other of dolomite. Dolomitic marble is much more resistant to acid attack than calcite marble. The color of marble ranges from the brilliant white of calcite to black, including blue-gray, red, yellow and green, depending upon the mineral composition. TYPICAL USES Marble has many decorative and structural uses. It is used for outdoor sculpture as well as for sculpture bases; in architecture it is used in exterior walls and veneers, flooring, decorative features, stairways and walkways. The way in which the stone is used may be a factor in limiting or controlling the severity of exposure. The use or function of the marble may also affect the feasibility of applying certain treatments, but type of use is not the primary factor in the major types of deterioration and damage to which marble is susceptible.