On Pyroxenic Components in certain Volcanic 



Rocks from Bonin Island 



by 



Yasushi Kikuchi. 



With Plate XIV bis. 



The following account of the Pyroxenic components in the rocks 

 of Bonin Island is based upon the investigation of materials collected 

 by myself, during a short visit to that island in November, 1887. 



Ogasawarajima or Bonin Island is the name applied to an island- 

 group of volcanic origin, apparently forming part of the chain of 

 of volcanoes which extends from Central Japan through the Shichitd 

 Group of the Prov. Izu. Themost important of the Bonin Island- 

 Group is that known as Chichijima (Peel Island, Lat. 27° 5' N., 

 Long. 142° 15' E. Green.) It has a spacious harbour known as 

 Futamikö (Port Lloyd) which without very good foundation has 

 been regarded as the relic of a volcanic crater. The geological col- 

 lections were principally made in this island, and also a few T in Ha- 

 hajima (Coffin Island) which is situated about 20 geogr. miles S.S.W. 

 of Chichijima. 



The volcanic activities seem to have subsided Ions: since in 

 these islands, and consequently their general features differ from 

 those of such islands of the Shichitd or Volcano Group which have 

 active volcanic cones. The interior is in some places covered 

 with dense tropical forest, among which rise numerous pointed 



