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. (See p. 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.

Different Forms Of Marble

Encrinal and Shell Marbles are those which derive their figure from embedded fossils, encrinites (lily-shaped plants with jointed stems), or fossils of ordinary shells.

Madrepore Marbles are made up entirely of fossil corals.

Ancient Marbles

Many of the marbles used by the ancients, and handed down to us in the shape of works of art, are not now known in their natural state.

Their markings and tints are frequently imitated in artificial marbles, and the ancient names are applied to the imitations.

Varieties

A good deal of the marble used in this country comes from the Continent.

Of the varieties found in England, the best known are those of various colours from Devonshire; black and grey marbles from Derbyshire; the Purbeck marble from Dorsetshire; Mona marble from Anglesea.

There are many varieties in Scotland, but they are chiefly used locally, and burnt for lime.

Ireland supplies marbles of all colours. Black from Galway, Kilkenny, and other counties; dark grey and sienna from King's County; white from Donegal; red from County Cork. The so-called Connemara marble is a serpentine (see p. 34).

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