206 AET. 3. — B. KOTO : 



they are right in special cases, as the éjecta may not be of a 

 single origin. Lackoix and Bkauns {Ioc. cit.) have already given a 

 summary of views on the modes of formation, which may be 

 grouped into the following headings : 



i. Intratelluric concretion of a trachytic or sye^nitic magma 



(Hussak). 

 ii. Contact-metamorphic product of the caught-up schists or 



sedimentaries (Bkuhns and Yamasaki). 

 iii. Crystallized mass ù'om syntectic magma under plutonic 



conditions (Tak. Kato). 

 iv. Imperfectly resorbed ancient rocks (Lacroix and Beauns). 

 Laceoix^^ made a close study of the éjecta from Pelée and La 

 Soufrière, which are akin to those of Sakura-jima. He is inclined, 

 to believe the cordierite to be mostly of secondary nature, formed 

 either in andésites or dacite magma, and recognized three possible 

 cases of its formation. 



a) Eesorption-relic of a rock-fragment, e.g., granite. 



b) A mineral newly crystalhzed from the melt of cordierite- 

 bearing rock-fragment. 



c) Newly crystallized in a cordierite -free rock, which suffered 

 chemical reaction of new magma in coming in contact 

 with it. 



Around the two volcanoes, Montagne Pelée and La Soufrière, 

 there are, according to Lacroix, diverse cordieritiferous blocks 

 derived from preexisting unknown rocks, viz:, 



«) Blocks composed of zonal feldspar (oligoclase-anortliite), 

 hypersthene, biotite, cemented with grains of quartz and 

 some glass. Miarolitic spaces are filled with cordierite. 



1) ' La cordierite dans les produits értiptifs de la IMontagne Pelée et de la Soufrière do 

 Saint- Vincent; Comiit. reivl. 137, p. 145-147, 1903. 



