MARBLE (from the Greek marmairein, to sparkle), a compact rock which, in its pure form, is composed entirely of carbonate of lime or limestone. In its best form it is a variety of calcite, the tiny crystal facets sparkling and flashing in the sun's rays; hence its ancient name. It is seldom found in perfect purity, the tractable qualities of the limestone allowing the introduction of many foreign substances during its formation. Thus there will be seen marble with streaks of various colors running through it, caused by the action of oxide of iron or other chemicals. Almost any limestone rock is commonly called marble, even certain varieties of granite, onyx, porphyry and rock largely composed of gneiss and mica-schist. True mar ble is a metamorphic equivalent of limestone, from which it has been produced by heat or pressure, or both.
Marble has been a favorite stone for form ing into statuary and for decorative work in buildings and monuments, frqm the very earliest ages. The Greeks, who were the first to endow this lifeless stone with marvelous genius in their statuary and bas-reliefs, were blessed with an almost inexhaustible supply of the very finest and purest marble yet discovered, on the island of Paros, in the iEgean Sea. This marble, so celebrated as possesses a peculiar waxy attribute which gave the statues formed from it a beautiful polish. The 'Venus de Med ici> was made from this stone, which is almost perfectly white. The Parthenon was built of marble of Pentelicus, which was a little more finely grained. The marbles of Carrara. were even then known but not generally put in use till later years, being still among the finest mar ble in the world, though having some gray streaks.
In many other parts of Continental Europe and in Great Britain are quarries of fairly pure marble. America has a large supply of this useful stone. Each year new occurrences of it are found in the Rocky Mountains, some of them pure white, others with variegated color ings. Perhaps the finest example of these won derful marbles of the Rockies is found in the new State capitol building of Colorado, at Den ver. In the eastern part of the United States there are many quarries of marble which have been in use for many years. Vermont is prof ably the seat of the largest quarries. Little of this marble is finely grained and white enough to answer for the sculptor's use, but it is ad mirably .adapted for ornamental purposes in architecture and for monuments for the dead. American sculptors still generally use the mar bles from Carrara, though the merits of the American product are becoming known. Ver mont, although one of the smallest States in the Union, exports more stone for commercial purposes than any other State, except one, Pennsylvania standing first. The money value in 1903 of Vermont's stone product was in ex cess of $6,000,000, a large part of it being in marbles of various grades.
The quarrying of marble is now carried on extensively, the use of machinery largely taking the place of the ancient hand methods. Fifty years ago the quarries of Rutland, Vt., still the largest in the world, were operated by ox teams and hand work of the crudest form. To-day, these vast quarries have an extensive outfit of electric cranes and derricks, which move the blocks of marble in any desired direction, easily and quickly, one of these traveling cranes hav ing a carrying capacity for 100,000 pounds. The stone is too easily broken to permit the use of blasting powders of any kind. This method is used in some of the Italian quarries, but causes great waste of material and is most unsatisfac tory. In the Vermont quarries, a machine called a “channeler'" has been found the best for eco nomical work and has been exdusively adopted. It consists of a row of long chisels set in a strong, traveling framework This gang of chisels vibrate up and down, cutting a channel in any direction desired in the face of the mar ble ledge. The channel can be made any rea
sonable depth, according to the size of block desired. When this channel, or groove, is suf ficiently long and deep, the machine is reversed and cross channels are cut and the bottom per forated. Then wedges are carefully driven in behind the block of stone and it gently falls over, to be lifted by a crane to the railroad cars or to that part of the quarry devoted to fur ther treatment of the output. As a rule, the stone is sent in its rough state to the purchaser, who dresses it himself. When the order is for monument work or some special design in archi tecture, the marble is treated at or near the quarry. In thus further treating the product, a toothless saw, or gang of saws, is used. The block of stone is placed on a horse, or plat form, and the saws set at work, the size of the cut being gauged by setting the saws close to gether, or far apart, as needed. A stream of water in which is mixed sea sand or other sharp, hard sand, falls upon each saw. The friction of the iron blade, aided by the sand and water, quickly cut's. up the marble into any de sired shape. Some marble cutters use saws of wire, but the best seem to be those made of strips of soft iron one-sixteenth of an inch thick and, when new, four inches wide. The marble wears down one of the saw blades very rapidly. When the blocks are thus sawn into the requisite shapes by the power gang-saws, they are then placed on tables and ground down to size, a small piece of marble being rotated over them by hand or power, water flowing over the surface being ground. With surpris ing facility, the marble yields to this treatment. Polish, in the final stages, is given by rubbing with wood or other soft material, and finally cloth. Much hand work is, of course, neces sary with the mallet and chisel and polisher, but all the rough, heavy work, which formerly made marble so costly and hard to obtain, is now done entirely by electric and steam power. One of the finishing rooms at the Rutland works, located at Proctor, Vt., is 1,000 feet long and contains scores of giant gang saws, cutting up the marble into various shapes. This one plant, the largest in the world, has an output of $3,000,000 annually and employs hundreds of men. Most of this output is of white marble, though brown, gray, green and other shades are found in profusion.
One ancient method of mining this delicate stone, still used entirely by the Mexicans in mitr ing onyx, is to drill holes in a line, insert plugs of some porous wood, pour in water and allow the wood to swell. This gently forces the precious stone free, without the least injury.
One quality of marble, not usually recalled, is its ability to withstand great heat safely. In the devastating fire in 1903 at Paterson, N. J., buildings built of granite crumbled and perished. Those of marble still stand, almost as good as ever. Its use is, therefore, becoming more and more general in erecting fireproof buildings in the large cities, the floors and often the entire inside wall and ceiling being overlaid with it.
Some really fine examples of craftsmanship in this line are found in the public buildings of New York City and elsewhere in America, not ably the new buildings of the Hall of Records and the Appellate Division of the Supreme Court, in New York. In the making of monu ments for the dead, marble is most extensively used. The floors of bathrooms, tops of toilet tables, basins for washing hands and clothes, tiling of various sorts — all these and a thou sand other household purposes find in marble their chief exponent. Probably more than $25,000,000 worth of finished marble products are used in the ljnited States annually, made from domestic quarries entirely. See also Rocxs.