CONSANGUINITY OF ERUPTIVE ROCKS. 603 



or segregations, of both the feldspathic and phosphatic types of 

 augite-syenite in a phonolitic nephelinite, apparently without 

 feldspar. The bulk of the iron ore at this place occurs as rounded 

 nodular segregations associated with apatite in a decomposed rock 

 which was evidently coarse grained and micaceous. This was 

 evidently not jacupirangite, but apparently some peculiar type of 

 nepheline or augite-syenite. Except for the absence of black 

 garnets it apparently corresponds closely with the ore-bearing 

 rock of Magnet Cove, Ark., described by the late Dr. J. F. 

 Williams. It may be noted in this connection that the same 

 character (absence of black garnet) distinguishes the jacupirangite 

 from the ijolith of Ramsay and Berghell. 



As in the Caldas region, there is at Ipanema evidence that 

 the eruptive action took place in the late Carboniferous or post-Car- 

 boniferous times. This coincidence of age at two of the localities 

 may perhaps justify the assumption (which cannot be directly 

 proven for lack at the other places of sedimentaries intermediate 

 between the very ancient and the very modern), that all of these 

 eruptive centers are substantially contemporaneous. Bearing on 

 this question of age, as also on that of consanguinity, is the fact 

 that in a region characterized by Devonian and probably also Car- 

 boniferous strata in Paraguay, Pohlmann has reported nepheline- 

 bearing basalt, and Dr. J. W. Evans has lately communicated 

 specimens of foyaite and augite-syenite from Pao de Assucar on 

 the Paraguay, proving that this mass, hitherto reputed to be 

 granitic, represents another eruptive center similar to those studied 

 in eastern Brazil. 



The evidence of consanguinity of foyaite and phonolite con- 

 sists of an intimate association within limited areas at all of 

 the localities mentioned, except Ipanema, where neither type 

 has as yet been found in a condition to be positively 

 identified ; of a direct passage to phonolite at the margins 

 of foyaite masses at Caldas ; of inclusions of phonolite in 

 foyaite at the same place and conversely of inclusions, evi- 

 dently formed in situ of foyaite in phonolite at Caldas and Tingua. 

 In this connection may be mentioned an inclusion of the type of 



