200 



ART. 3. — -B. KOTO 



dierite, and the tufts of slllimanite like those in porcelain are also 

 found within the body of the same mineral. 



The general mass is built up of polarizing crystahine grains 

 (0.04 mm.) of plagioclase imbued with colorless glass w^hich contains 

 on the other hand superabundant vacuoles (PL XXII. Fig. 3). Empty 

 hollows (0.2 mm.) are distributed through the mass, which cause 

 vesicular texture. The éjecta are like stoneware burnt to about 

 1,300°C, just before the ebullition (so-called storm) of gases from 

 a melt. 



The third type (PI. XXII. Fig. 4-5)— the compact lithoidal 

 modification — is a porcelain-like projectile, occurring frequently in 

 considerable size, often stained 

 yellow or brown due to decom- 

 position of pyrrhotite (Text- fig. 

 45). The éjecta are peripherally 

 traversed with contraction -cracks, 

 and break with conchoidal frac- 

 ture having semitranslucent 

 edges, while internally passing 

 into the vesicular second type. 

 This is the normal type 

 (PL XXIL Fig. 4) of what we 

 usually call the cordierite- bearing 

 éjecta with violet spots of visi- 

 ble cordierite (PI. XXI. Fig. 1). 



Microscopically, it looks 

 very much like the preceding 

 second type, except the violet 

 color of heterogeneous granulated 

 cordierite and the scarcity of macroscopic pores. 



Kig. 45.^ — A lithoidal ceramicite. 

 Loc. : Koike. 16 x 9 cm. 



