C 543 ] 



2 or 3 inches in diameter, are come across. Such a deposit 

 has been recently discovered in the mica mines of the 

 Koderma forest, Hazaribagh, and it promises to be of great 

 value to Indian Agriculture. Messrs. Ewing & Co. are selling 

 the uncrushed mineral at Rs. 2 per maund and in the crushed 

 state at Rs. 3 per maund. As the crushing can be done with 

 an ordinary dhenki provided with a block of granite or basalt 

 at the base of the mortar, at a cost of about 2 annas a maund, 

 it is best to procure the crude mineral. In pure state, apatite 

 contains 90 to 92 per cent, of tricalcic phosphate, and its 

 formula is either 3CaoP 2 Ox 4- CaCl 2 or, 3Ca 3 P 2 Os -f CaFo, 

 according as to whether the mineral contains Chloride or 

 fluoride of Calcium, though it frequently contains both. In 

 the natural state, in which it occurs in Hazaribagh, it contains 

 many impurities, e. g. quartz and mica ; crystals of felspar 

 being also associated with the mineral. In this state, Mr. 

 D. H. Holland, Superintendent of the Geological Survey of 

 India, has found 76 per cent, of tricalcic phosphate in the 

 Hazaribagh apatite. 



873. Occasionally phosphates occur in rocks and soils in 

 the form si phosphorite crystals (CasPgOg) without being com- 

 bined with calcium chloride or fluoride. 



874. Weavilite, which is hydrated aluminium phosphate, 

 is another fairly common mineral, but we can ignore consi- 

 deration of this for manurial purposes, as it does not occur in 

 sufficient abundance anywhere. 



875. In the Nepaul valley there is a clay which is actual- 

 ly used as manure, which is rich in a phosphatic mineral 

 (vivianite}. 



876. Hard phosphatic nodules occur in fair abundance at 

 Trichinopoly. These contain nearly 57 per cent, of GasP-jO* 

 (equivalent to about 26 per cent. P 2 Os) and about 16^ per 

 cent, of CaCOa. They are as difficult to crush as coprolites. 



877. Coprolites are probably fossil dung of extinct 

 animals* There are rich deposits of these in many countries, 



