Stone has been used as a structural material since the earliest days. Almost of all famous buildings of classic times, of the medieval and Renaissance periods and of the eighteenth and early nineteenth centuries were erected of stone masonry. In some places stone was used because of the scarcity of timber, bin in other places stone was preferred because of its durability.<br>The stones which are usually used for masonry work are as follows:<br>1) Granite is very hard, strong and durable. It is used particularly for basements base courses, columns and steps and for the entire facades. Its colour may be gray yellow pink or deep red.<br>2) Sandstone. Sandstone is composed of grains of sand or quarts cemented together. Sandstones form one of the most valuable materials. The durability of sandstones depends very largely upon the cementing material.<br>Thus, there are different kinds of sandstones. Many sandstones are exceptionally hard and are selected for steps, sills etc. The excellent state of preservation of many ancient buildings built of this stone is evidence of this. But city buildings constructed of sandstone often assume a drab appearance owing to the dark colour. It is an excellent material for concrete aggregate.<br>3) Marble is a crystalline stone chiefly used for decorative purposes<br>White and black marbles are used for ornamental decoration where the beauty of the marble is shown to its best advantage.exclyexceptionally hard
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