It is better to have the blocks cut to the desired forms in the quarries; first because it is easier to square and dress the stone while it contains the moisture of the ground or "quarry-sap;" also because the local men, being accustomed to the stone, are able to dress it better and more economically, and part of the work can be done by machinery, generally to be found at the principal quarries. Moreover, the bulk of the stones being reduced by dressing, the cost of carriage is saved, without much danger of injuring the arrises in transit, as the stone is very hard.
1 Page's Practical Geology.
2 Wray On Stone.
Granite is used chieily for heavy engineering works, such as bridges, piers, docks, lighthouses, and breakwaters, where weight and durability are required. It is also used especially for parts of structures exposed to blows or continued wear, such as copings of docks, paving, etc. The harder varieties make capital road metal.
In a granite neighbourhood the stone is used, for ordinary buildings; but it is generally too expensive in first cost, transport, and working, and is therefore reserved for ornamental features, such as polished columns, pilasters, hea\y plinths, etc.
Granite is found in Aberdeenshire, Kirkcudbrightshire, Argyleshire, and the Islands of Mull and Arran. Also in Cornwall, Devonshire, Leicestershire, Cumberland, and the islands of Guernsey and Jersey. The Irish granites occur chiefly in the counties of Wicklow, Wexford, Donegal, and Down.
The Scotch Granites are most esteemed for beauty and for durable qualities, especially those from the two great districts of Aberdeen and Peterhead - the stone from the former is generally grey, and that from the latter red.
The other best known varieties of Scotch granites are those from Eubislaw, Stirling Hill, Dalbeattie, Ross of Mull, Kemnay, Kinsteary, etc.
The Cornish and Devonshire granites, sometimes called moorstones, have not so high a character. They contain a large proportion of felspar, which in some cases weathers very badly. The potash felspar of these granites, when decomposed, turns into Kaolin or porcelain clay.
The Leicestershire Granites are, generally speaking, syenites - very hard and tough, difficult to dress, and therefore not much used for building purposes. They are well adapted for paving sets, and make capital road metal.
Jersey and Guernsey Granite is also syenitic. It is a good weathering stone, very hard, durable, used for paving purposes, but rather apt to become slippery.
The Irish Granites are very numerous. Grey varieties are obtained from Wicklow and Dublin. Those of a reddish tint from Galway. A good bluish grey granite comes from Castle Welland, County Down; Counties Donegal and Mayo produce good red granites. Several colours and varieties come from Carlow. Newry supplies a greenish syenite.1
1 Wilkinson's Practical Geology of Ireland.
The following Tables give a list of some of the principal Granite Quarries in Great Britain and Ireland. The quarries are very numerous, but it is hardly worth while to mention many of them in the following Tables: -