Marble, a snowy white or richly colored ornamental stone. Polishing brings out the handsome grain, network of delicate veins, and cloudy hues that give marble its special beauty. About 100 named varieties of marble are produced in the United States. The most important quarries are in Georgia, Vermont, and New Mexico.
Inscribed blocks of marble are widely used as grave markers. Architects use marble slabs as a durable, attractive veneer on the walls and floors of public buildings. Marble also is used for sanitary fixtures, and is carved into table tops, mantelpieces, lamp bases, and desk ornaments. Bits of colored marble are used in mosaics and stucco. Playing marbles formerly were made of marble but are now made of glass, clay, or other substances.
The purest white marble has been used for centuries in statuary and as decorative building stone. The marble quarried near Carrara, Italy, is famous for its high purity and fine grain. It has been highly prized as statuary marble since ancient times.
The term marble is used in two senses. To geologists, marble is limestone (calcium carbonate) or dolomite (magnesium carbonate) that has undergone changes due to heat and pressure. To stonecutters and builders, however, marble is any hard, crystalline rock, not classed as a granite, that will take a high polish and can be produced in sizable blocks. Thus, serpentine marble is mostly magnesium silicate, and onyx marble is a banded form of calcite deposited in springs. Tennessee marble is unmetamorphosed limestone of exceptional quality.
The black veins in many types of marble are caused by carbon impurities. Red and yellow marbles contain iron oxides. Green marbles contain mica and talc.
Marble closely resembles granite in hardness, weight, and strength, but marble is more easily corroded by acids and stained by rust or oil. Marble and granite are quarried by the same techniques.