12 ART. 12. — B. KOÏÔ : 



of absorption ; c^a > h ; p > v. This may be due to secondary 

 enlargement, being represented by a kind of amphiboles. 



The greenish color of the rock is mainly due to the presence of 

 serpentine. Xenomorphie, pistachio-green epidote occurs associated 

 with diopside, giving a greenish yellow tinge to a certain portion of 

 the rock. Our rock in point of mineralogical composition has the 

 combined characters of regional (serpentine) and contact metamorphisms 

 (diopside). 



The (/9) yarnetite (PI. III. figs. 1 and 2) is, like the preceding, 

 a light-grayish, fine-granular and hard rock, being composed of an- 

 dradite (the lime-iron garnet), calcite and diopside, besides small quan- 

 tities of epidote, titanite and (?) axinite. The dominant component is 

 andradite. The garnet is o'einarl-able in showing the well-defined 

 divisions of the optical field owing to anomalous double-refraction 

 (PL III. fig. 2). Brögger says that anomalous garnet occurs in veins, 

 dykes and contact rocks, and the present garnctite is a special case in 

 his category. It is also said that anomalous garnet often appears in 

 connection with zonal structure and isomorphic shells^'. The Korean 

 garnet has a faint zonal "^ structure (PI. III. fig. 1) in some optical 

 fields, but in the onajoritj/ it is devoid of it. The lime-iron-garuet 

 shows not only an anomalous behavior, but also very pronounced 

 optical pyramids which, when seen between crossed niçois, appear 

 exactly like a tessellated mosaic work (figs. 1 and 2), each part ranging 

 from 3 to 5 mm in size. The optical checkered work makes up a 

 large part of a slide, and it is entirely impossible to set a limit to 

 the grains that compose the main bulk. The phenomenon of double- 

 refraction corresponds to the rhombic dodecahedron type, with homo- 

 geneous extinction of light parallel to tlie diagonals of the rhomb. 

 There are, however, oblique triangles which extinguish light also 



1) Z. X,, re, 1890, S. 172. Also Eosenbusch-Wülfing, " Pliysiograpliie", Bd. I., 2. 

 S. 21. 



2) A specimen lately received from Mr. Kochibé has a beautiful zonal structure, but 

 shows no signs of optical pyramids. ïlie anomalous o[)tical field and the zonal structure 

 seem to exchide each other, at least in the Hol-gol specimens. 



