220 NEW RED SANDSTONE. 



Mansfield White and Red Sandstones. The terrace at Trafalgar Square is 

 paved with the white sandstone. The red sandstone is considered one of the 

 best building-stones in the kingdom. Fine soft sands (Quicksand) at the base 

 of the Magnesian Limestone occur at Glasshoughton and Pontefract, and they 

 have been largely worked for moulding. 



The Magnesian Limestone has been used for road-mending ; and it is largely 

 burnt for manure, the limes of Kinnersley, Knottingley, Warmsworth cliff near 

 Doncaster, Brancliff, Roche Abbey, Brotherton, Ferrybridge, Mansfield, etc., 

 being celebrated for agricultural purposes. The calcareous conglomerates of 

 Worcestershire, to the east of the Lickey and Clent Hills, have also been burnt for 

 lime. Slabs of Magnesian Limestone have been polished at Knaresborough, 

 Worksop, Sunderland, etc. The Lower Magnesian Limestone near Tadcaster 

 contains beds of hard flinty rock, termed Calliard or Galliard, which is used for 

 road-metal. In some of the chemical works on the Tyne the dolomites of 

 the northern counties are used for the production of carbonate of magnesia ; 

 while the magnesian limestones of Marsden are taken in considerable quantities 

 to Sunderland, where, being treated with sulphuric acid, the magnesia is dissolved 

 out, and from the liquor obtained, Epsom salt (sulphate of magnesia) readily 

 crystallizes. A considerable amount of Epsom salts is thus obtained.' 



Red sandstones have been quarried at Alveley, and Highley, south of Bridge- 

 north, for the manufacture of grindstones. 



Staffordshire blue bricks are manufactured from dark red clays above the Coal- 

 measures, which may be due in part to the degradation of basaltic rocks.^ The 

 deep blue colour is produced by sprinkling the bricks before firing with "iron 

 swarf," that is, dust of stone and iron. The iron becomes oxidized and combines 

 with the silica of the brick to form silicate of protoxide of iron. Glazing is 

 effected by throwing common salt into the fire-holes of the kiln, as soon as the 

 burning is completed.^ 



The middle Permian marls are used for brick-making, at Cinderhill, and near 

 Buhvell, Hucknall Torkard, between Mansfield and Sutton-in-Ashfield. In the 

 neighbourhood of Doncaster, Ferrybridge near Pontefract, and near Tadcaster, 

 the lower Permian marls have yielded gypsum, formerly worked for Plaster of 

 Paris. The red shales above the Magnesian Limestone have been worked for 

 gypsum at Coat Hill, Eden Lacy, and Kirkby Thore near Carlisle. Rock-salt 

 occurs in the marls at Middlesborough in Yorkshire, where a bed lOO feet in 

 thickness has been penetrated ; gypsum also occurs here. The Permian age of 

 these beds has, however, been questioned.* 



Nodules of Haematite have been obtained in large quantities from Measham in 

 Derbyshire, and also from the neighbourhood of Ashby-de-la-Zouch. They have 

 been employed under the name of " bloodstones,"^ as burnishers, and have been 

 manufactured into " ironstone jewellery." (See p. 2i8.) 



The Magnesian Limestone forms light, arable, and dry soil. It was termed the 

 Redland Limestone by William Smith. 



^ R. Hunt and F. W. Rudler, Descriptive Guide to the Museum of Practical 

 Geology, edit. 4, p. 40. 



'■^ C. Beale, Midland Naturalist, vii. 126. 

 ^ J. Percy, Metallurgy, 1875, p. 151. 



* E. Wilson, Midland Naturalist, iv. 188. 



* The true Bloodstone or Heliotrope is a jaspery variety of quartz of deep 

 green colour, interspersed with red spots. Bristow, Glossary of Mineralogy, p. 46. 



