82 Y. KIKUCHI 



Thus the Rhombic Pyroxene under consideration may be called 

 Bronzile. The Rhombic Pyroxenes which have been recognised in 

 Andésite and other effusive rocks, are so far usually of the more 

 ferriferous kind known as Hypersthene. A well crystallized variety 

 corresponding to the composition of Bronzite has hitherto been un- 

 known to the writer. It ought to be remarked however, that the 

 the ratio of the two silicates Fe Si 3 and Mg Si 3 seems to vary to a 

 certain extent in the different varieties of rocks in which they occur. 

 Thus it is found that the specimens found in the dark porphyritic rocks 

 are probably more ferriferous, as shown by their stronger pleochroism. 

 It has also been indicated on page 79 that in the rock of Miyanoura, 

 the crystal sometimes occurs built up of isomorphous layers, (fig. 12) 

 also indicating this variation in chemical composition. 



The mean specific gravity was found to be 3* 3 05 



With regard to hardness, it was found that the sharp edge of the 

 Pyroxene can scratch the Adularia Felspar with ease ; thus we may 

 consider H = 6. The pyramidal face e, which is across the direc tions 

 of the well-defined cleavage, is decidedly harder than faces lying in 

 the prismatic zone ; the latter can be scratched with difficulty with a 

 sharp edge of the Felspar, but we have never succeeded in scratching 

 the former. Thus on this face H — 6*5. 



Thin pieces subjected to the tip of blow -pipe flame fuse at the 

 edge, into a dark globule. 



A Green Augite. 



The occurrence of a light greyish green coloured Augite in 

 paraliel-intergrowth with the Rhombic Pyroxene has already been 

 considered. In some specimens of the glassy rock, we find the former 

 more abundantly than the latter. At first sight, these two minerals 

 when found together seem to be almost indistinguishable from each 



