PKINCIPAL PHOSPHATE DEPOSITS. 23 



7. Garcl and Ardeche Phosj^hates. — The Gard deposits are 

 chiefly phosphorites, the formation of which has been contemporane- 

 ous with those of Quercy. They are found in irregular excavations 

 amongst the compact hmestone of the Urgonian age. The workings 

 are underground. The chief producing centres are on the lands of 

 the communes of Tavel and Lirac. There are a 'so deposits of 

 nodules in Saint-Julien-de-Peyrolas and Salazac, also in the de- 

 partment of Ardeche at Saut-de-l'Eygue, la Eousette, Beyne, etc. 

 Production almost nil. 



8. Drome and Isere Phosphates. — In Drome they chiefly work 

 the Greensand nodules at Saint-Paul-Trois-Chateaux in the district 

 of Montehmar. The content of these nodules does not exceed 55 

 per cent of tribasic phosphate of lime ; it averages 45 per cent. The 

 workings are unimportant, are solely in the open air, and consist of 

 screening the nodules and scrubbing them in water to separate 

 adhering sand. In Isere there are fossiliferous and phosphatic 

 beds (Gault) of great regularity, but the rock is sometimes so com- 

 pact that the nodules cannot be washed and enriched by simple 

 economic means, such as screening and scrubbing, which are the 

 only methods that can be applied to material so poor in value. 



'9. Pyrenees or Arieges Phosphates. — These phosphates, described 

 by Dr. Levat in a memoir presented to the Academy of Sciences, 

 form a vast bed developed in the valleys of Bonnes, Luchon, Salat, 

 in the neighbourhood of Prades, ascending tow^ards the north in 

 les Corbieres as far as the environs of Cannes. Pyrenees or x\rieges 

 phosphates have a brilliant black appearance recalling that of anthra- 

 cite. The composition of the bed is characterized in its rich parts 

 by numerous black, brilliant, usually flattened nodules consisting of 

 almost pure phosphate of lime and testing 65 to 75 per cent of tribasic 

 phosphate of lime. The gangue encrusting these nodules is itself 

 phosphatic. Moreover, there has been found in it an important 

 amount of organic matter containing organic nitrogen in the pro- 

 portion of 11 lb. per ton. The extent of the bed reaches 8 to 10 

 metres (26 to 33 feet). The nodules are concentrated sometimes 

 on the roof, sometimes on the wall of the deposit. 



11. Belgium.— About 1874, Cornet discovered at Mesvin and at 

 Ciply near Mons, below the landenien sands, a bed of 8 to 10 metres 

 thick of brownish, friable, slightly coherent chalk containing 75 per 

 cent of brown grains of carbonate and phosphate of lime, the largest 

 of which are not bigger than a pin's head. This speckled chalk, 

 known in the district as brown chalk {craie brune), contains 25 to 

 30 per cent of tribasic phosphate, with a slight enrichment at the 

 base. It occurs at a higher level than the Beauval chalk. In the 

 upper part it exhibits pockets, in which there are found masses 

 of pudding-stone cdAledi poudingue de la Malogne, consisting of brown 

 coloured nodules containing 50 per cent of phosphate, cemented 



