198 ART. 3. — B. KOTÔ : 



from the Laacher See.^^ The garnet-bearing plagiohparitic efFusives 

 containing the same mineral are made known from Futakami- 

 yama, Prov. Yamato,'^ and Obora-yama,"^^ Prov. Isé, both being 

 probably the same kind of rocks as those from Campiglia Mari- 

 tima/^ Lipari,^^ Cabo di Gata,"^ and Tian-shan/^ 



The éjecta fi^om Sakm^a-jima may be divided into 5 types, 

 according to granularity. 



Trie first type (PL XXII. Fig. 2) — the saccharoidal modification — 

 is pure white and saccharoidal with blue flecks (4 imn.) of short- 

 prismatic cordierite and dark, irregular spots (1 mm.) of pyrrhotite. 

 It crumbles easily between the fingers like the saccharoidal micro- 

 tinite already mentioned (p. 190, the « type). 



Microscopically, cordierite is porphyritic and anhedral or sub- 

 hedral. It is peripherally resolved into subr octangular microcrystals 

 arranged parallel to the c-axis of main crystals (PI. XXII. Fig. 3), 

 sometimes, however, being shghtly divergent (PI. XXII. Fig. 4) like 

 digitate crystals or ' fingered aggregate ' of andalusite in contact 

 rocks, indicating that the larger cordierites were being formed 

 during the turbulent state of the magma within the vent or in 

 viscous lava. It is negative and bluish, parallel to c, and charac- 

 teristically contains pores in the centre (PI. XXII. Fig. 2, c). In other 

 cases the cordierite is entirely built up of minute grains of the 

 same mineral (PI. XXII. Fig. 4). Irregular clumps of pyrrhotite of 



1) R. Brauns, ' Die kristallinen Schiefer des Laacher Seegebietes und ihre UmbUduug zu 

 Sanidinit.' 



2) M. Üyu, ' Report on the A^'olcano Fiitagami-yama.' Puhlicatlons Imp. Earthq. Invest. Com., 

 No. 27, Tokyo. (Japanese) 



3) Found during revising a student's slides. 



4) Zeitschr. d, deutch. <jeol. Ges., 1861, S. C41 ; 1868, S. 327. 



5) A. Bergeat, X. J. BBd. XXX. and Bd. H. 1895. 



6) A. Osann, Z. d. deutch. geol. Ges., XL. 1888. 



7) In the Bogdo-Ola near Urumtsi, the femic diabase and salic keratophyres occur as- 

 sociated with the mediosilicic effusive of dacite besides Cordierite-liparite. G. Ghinger, 'Die 

 Gesteinswelt der Bogdo-Ola.' Inaugural Dissertation, München, 1912. 



