Marble is the name practically given to any limestone which is hard and compact enough to take a fine polish.

The name is frequently, however, erroneously applied to other stones, such as serpentine, merely because they are capable of being polished.

Some marbles - such, for example, as those from Devonshire - will retain their polish indoors, but lose it when exposed to the weather.

Marble is found in all great limestone formations. It consists generally of pure carbonate of lime. The texture, degree of crystallisation, hardness, and durability, of different varieties vary considerably.

Marble can generally be raised in large blocks. The handsomer kinds are too expensive for use, except for chimney-pieces, table slabs, inlaid work, etc.

The less handsome varieties are used for building in the neighbourhood of the quarries.

The appearance of the ornamental marbles differs greatly, Some are wholly of one colour, others derive their beauty from a mixture of accidental substances - metallic oxides, etc., which give them a veined or clouded appearance. Others receive a varied and beautiful "figure" from shells, corals, stems of en-crinites, etc., embedded in them.

Uses

Marble is used in connection with building chiefly for columns, pilasters, mantelpieces, and for decoration.

The weight of marble makes it suitable for sea-walls, breakwaters, etc., when it is cheaply obtainable, but some varieties are liable to the attacks of boring molluscs. (Seep. 10.)

In the absence of better material marble may be used for road metal and paving setts, but it is brittle and not adapted to withstand a heavy traffic. Roads made with it are greasy in wet weather and dusty when dry.