Sandstones are used for paving, general building purposes, carving, or for heavy engineering works, on account of their great power to resist compression, some of the best qualities being capable of resisting a pressure of between 600 and 700 tons per square foot before they crack even, and more before being crushed completely. They are hard, though free-working, and durable; they absorb from 8 to 10 per cent of water; and their weight is from 120 to 170 lbs. per cubic foot.
A good sandstone should be of an even grain, and crystalline in texture. When chipped into clear water, and stirred about, it should not make the water muddy; and it should absorb no more than 10 per cent of water when poured on to it, while for work requiring strength it should be capable of taking, at the very least, 550 tons per square foot in compression before fracture takes place.
The best and most well-known sandstones are as follows: -
Craigleith stone is the most durable in Great Britain, found near Edinburgh. It contains 98 per cent of pure silica, with 1 per cent of carbonate of lime. It is of a greyish colour, very hard, durable, and strong - some beds being three times as strong as Aberdeen granite - and of such a fine grain that it may hardly be called a grit. It takes a very fine arris, and never wears smooth. Its principal use is for steps, paving, etc., and heavy engineering works requiring great strength.
The Derbyshire sand or gritstones are a very useful and good stone, weathering well, carrying a fine arris and nice even-coloured face, especially the Burntwood and other fine Darleydale qualities, which have been proved to withstand a smoky atmosphere where other stones have decayed; and the coarser qualities, found near Matlock Bridge, have great powers of resistance to crushing, rendering them most suitable for pad-stones, engine-beds, and column-bases. Stone blocks of such a size as 8 feet square and 3 feet deep are often procured out of the best quarries.
Forest of Dean stone is found in Gloucestershire, among the coal measures. It is both soft and hard, according to bed, the best yielding a hard stone, of a fine grit, which can be quarried in large blocks.
Mansfield stone is found in Nottinghamshire, and of two kinds, respectively red and white in colour. It is a close crystalline gritted stone, quarried in large blocks, has a nice uniform appearance, is easily worked, weathers well, and is suitable for dressings, pavings, stairs, and ornamental work generally. Mansfield stone is called a dolomite, and contains almost equal quantities of the carbonates of magnesia and lime.
The Yorkshire stones are of many varieties, including Bramley Fall, Scotgate Ash, Parkspring, Robin Hood, Elland Edge, Howley Park, and Spinkwell; most of which are good hard stones, suitable for paving, dressings, pad-stones, and engineering work. They work and weather well, stand considerable wear, and are close and even in the grain, brown or blue in colour, and of numerous shades.
The Yorkshire quarries are worked by open workings, or by shafts, in a similar manner as coal, some of the beds being sandstones of the lower coal measures. The depth of stone varies from a few feet to over two hundred feet below the surface. The quarries produce "blocks" and "flagstones" - the latter being converted into stills for chemical works, flagging for streets, kitchens, passages, etc.; while the thinner lifts are used as roofing " slabs," the small pieces of the flags being dressed into wall stones.
The block stone produces the thicker kinds of flagstone, and is sawn into slabs for use in staircases, chimneypieces, dressings, and monumental work; the waste or smaller pieces being converted into "setts" and "paviors" for streets.
Of the brown and blue varieties found, it must be understood that the latter is by far the better stone where strength is required, it being capable of .taking a weight of 668 tons before cracking, and 728 tons before being crushed, whereas brown will only bear the pressure of 484 and 514 tons respectively, these results being obtained on 6-inch cubes.
Runcorn is a. good, useful, strong, durable, red building stone, found near Liverpool, being free-working, and of nice open grit Cefn, a yellow grit stone, of fine grain, is found in Wales, and used for most building purposes.
Hollington is another good weathering sandstone, either red or white in colour, found in Staffordshire, and very often used for general building purposes.