562 S. KOZU 



olivine as megascopic phenocrysts. This mineral is 2 mm. in 

 diameter, and is also fresh in aspect. 



Microscopical characters. — The mineral components are olivine, 

 augite, plagioclase, magnetite, and apatite, with phenocrystic 

 quartz. The microscopic phenocrysts are not abundant; among 

 them the olivine is most common, then follows the augite in nearly 

 equal amounts; the plagioclase occurs subordinately. The ground- 



FiG. 1. — Quartz-basalt. X§- The white grains are quartz. 



mass is hypocrystalline in texture and consists of lath-shaped 

 plagioclase, prismatic or granular augite, and magnetite crystals, 

 with abundant interstitial glass of light-brown color, clouded by 

 numerous globules. 



Olivine belongs to the earlier crystallization among the mineral 

 ingredients of the rock, and is almost free from inclusions with the 

 exception of a few crystals of magnetite and glass, which are very 

 rare. It forms anhedral to subhedral shapes with finely ragged 

 outline, and about it minute granules of pyroxene may be observed. 



