ON ANOIITHITE FEOM MIYAKE.JIMA. 



43 



The figures produced by fluoric acid are nearly all elliptical (fio-. 

 15, 16, h) while those produced by hydrochloric acid are round-sided 

 asymmetric triangles (fig. 15, K),^^), one of the sides being apparently' 

 parallel to the direction of the Pericline-lamella^. Fig. 17 is intended 

 to show the relative position of these figures with reference to a 

 simple primitive form consisting of the faces P, M, and y ; the figures 

 on P' and M' being supposed to be looked at through the face y. 



For the chemical analysis of the mineral, I am indebted to Mr. 

 Y. Kitamura, of the Geological Survey. The sample taken for the 

 analysis was obtained from fresh specimens of separate crystals. The 

 lava-coating was removed, and transparent portions of the interior 

 carefully selected. The small grains of Olivine attached to the 

 powdered sample were removed by means of Thoulet's solution, until 

 the microscope showed the ideal purity of the sample. The result of 

 the analysis is shown below in Column I. For the sake of com- 

 parison, we quote here in Column II, the analysis of a similar kind of 

 Anorthite as that of Miyake, from a porphyritic volcanic rock of 

 Tönosawa in Hakone, given by Wada.* 



1. c. p. 33. 



