THE NONMETALLIC MINERALS. 373 



spar of the granites. They are mined only from open cuts and in th(> 

 supin-tieial more or less decomposed portions of tlie rock, to which 

 they are believed to be mainly limited, having originated, as elsewhere 

 indicated, through a segregation of the phosphatic material dissolved 

 by meteoric waters from the surrounding granite and sul)se(iuently 

 depositing it in preexisting fissures. The percentage of tricalcic 

 phosphate is given as varying between 60 and 80 per cent, 



Ifuly. — Phosphatic deposits consisting of coprolites, bones, etc, 

 imbedded in a porous Tertiary limestone occur between Gallipoli and 

 Otranto, Cape Leuca, Avest of the Gulf of Taranto, on the Italian 

 coast. There are two beds having a thickness of 19^ and 31i inches, 

 respectively, and which have been traced for a distance of some 160 

 yards. Analyses .show them to be of low grade, rarely carrying as 

 high as 10 per cent PgO^. 



Tunk. — Phosphatic nodules in the form of cylindrical coprolites 

 and clustered aggregates have been found in Tertiary strata covering 

 considerable areas in the region south of Tunis, The coprolite nodules 

 are stated to carry as high as 70 per cent of calcium phosphate, and 

 the clustered aggregate some 52 per cent. 



Rnsi^ia. — Rich phosphate deposits of Cretaceous age occur in the 

 governments of Smolensk, Orlow, Koursk, and Vorouez, between the 

 rivers Dnieper and the Don in European Russia. The deposits lie 

 mostly in a sandy marl, underlying white chalk and overlying green- 

 sands, which also carry beds of from 6 to 12 inches thickness of phos- 

 phatic nodules. The nodules are dark, often nearly black, in color 

 and are intermixed with gray, brown, and yellow sands. The depth 

 of the beds below the surface is variable, Yermolow ^ divides the 

 deposits into two groups, the first presenting the form of separate 

 nodules, rounded or kidne3^-shaped, of variable size, and black, brown, 

 gray, or green in color. The second is in form of an agglomeration 

 of large nodules cemented together into a sort of flag, which used to 

 be quarried for road purposes. The nodules in this agglomerate are 

 richer in phosphoric acid when most dense and of a deep black color, 

 the sandy varieties being comparatively poor. The cement carrying 

 the nodules contains numerous fossil bones, shells, corals, etc. , which 

 are also phosphatic. The samples yield about 30 to 60 per cent phos- 

 phate of lime. Other deposits occur south of Saratov, on the Volga 

 (Specimen No. 52067, U.S.N.M.); at Tambov and Spask, where the 

 overlying rock is a greensand in place of the chalk; Moscow; east of 

 Novgorod, on the Msta; at Kiev, on the Dnieper; Kamenetz, Podolsk, 

 on the Dniester, and at Grodno, on the Niemen. 



Maltese Islands.^ — Nodular phosphates occur in Miocene beds on the 



' Recherches sur les Gisements de Phosphate de Chaux Fossil en Russie. 

 2 J. H. Cooke, The Phosphate Beds of the Maltese Island. Engineering and Min- 

 ing Journal, LIV, 1892, p. 200. 



