Water 3.976 Organic matter 2.001 Calcium sulphate 2.026 Calcium carbonate 28.121 Calcium fluoride not determined Calcium and magnesium phosphate 53.996 Magnesium carbonate 0.423 Aluminic phosphate 1.276 Ferric phosphate 6.182 Silica 0.773 ------ 98.734
An ichthyo-coprolite from Tenby was found to contain 15.4% of phosphoric anhydride. The pseudo-coprolites of the Suffolk Crag have been estimated by Herapath to be as rich in phosphates as the true ichthyo-coprolites and saurio-coprolites of other formations, the proportion of P2O5 contained varying between 12.5 and 37.25%, the average proportion, however, being 32 or 33%.
Coprolite is reduced to powder by powerful mills of peculiar construction, furnished with granite and buhrstones, before being treated with concentrated sulphuric acid. The acid renders it available as a manure by converting the calcium phosphate, Ca3P2O8, that it contains into the soluble monocalcium salt, CaH4P2O8, or "superphosphate." The phosphate thus produced forms an efficacious turnip manure, and is quite equal in value to that produced from any other source. The Chloritic Marl in the Wealden district furnishes much phosphatic material, which has been extensively worked at Froyle. In the vicinity of Farnham it contains a bed of "coprolites" of considerable extent and 2 to 15 ft. in thickness. Specimens of these from the Dippen Hall pits, analysed by Messrs J. M. Paine and J. T. Way, showed the presence of phosphates equivalent to 55.96 of bone-earth (_Journ. R. Agric. Soc. Eng._ ix. 56). Phosphatic nodules occur also in the Chloritic Marl of the Isle of Wight and Dorsetshire, and at Wroughton, near Swindon. They are found in the Lower Greensand, or Upper Neocomian series, in the Atherfield Clay at Stopham, near Pulborough; occasionally at the junction of the Hythe and Sandgate beds; and in the Folkeston beds, at Farnham. At Woburn, Leighton, Ampthill, Sandy, Upware, Wicken and Potton, near the base of Upper Neocomian iron-sands, there is a band between 6 in. and 2 ft. in thickness containing "coprolites"; these consist of phosphatized wood, bones, casts of shells, and shapeless lumps. The coprolitic stratum of the Speeton Clay, on the coast to the north of Flamborough Head, is included by Professor Judd with the Portland beds of that formation. In 1864 two phosphatic deposits, a limestone 3 ft. thick, with beds of calcium phosphate, and a shale of half that thickness, were discovered by Hope Jones in the neighbourhood of Cwmgynen, about 16 m. from Oswestry. They are at a depth of about 12 ft., in slaty shale containing Llandeilo fossils and contemporaneous felspathic ash and scoriae. A specimen of the phosphatic limestone analysed by A. Voelcker yielded 34.92% tricalcium phosphate, a specimen of the shale 52.15% (_Report of Brit. Assoc._, 1865). Phosphatic beds, supposed to have had a coprolitic origin, are found in the Lower Silurian rocks of Canada.