ON THE SO-CALLED CRYSTALLINE SCHISTS OF CHICHIBU. 91 



hy fibrous-scaly lamellae of a greenish sericite. Pleochroism is dis- 

 tinct and intense nearly in the direction of the vertical axis. Epidote 

 crystals arrange themselves with the orthopinacoid parallel to the 

 plane of the schistosity of the rock, consequently its transversal 

 section exhibits a vicinal clinopinacoid of epidote as an imperfect 

 rhomboid, tapering at both ends. 



Our epidote belongs to a common type in its crystal-form by 

 having M and r or oV and Poo as the predominating faces ; consequently 

 the clinopinacoidal section presents a flat rhomboid (M : r:=116°); 

 while the manganese-epidote which also makes its appearance in tliis 

 variety of rock, is of a nearly rectangular rhomboid, when viewed in 

 a similar section as the preceding. This is due to the fact that in the 

 latter, Ï and i constitute the predominating faces which make with 

 each other an ano-le of 99° or 81°. 



Irreü^ularities of outline mainlv result from the neiohbourino- 

 quartz grains, which push inwards into the substance of the crystals, 

 and when the interior become full of such large, vitreous quartz- crvstal- 

 loids, the epidote appears not unlike a melilite in l)asalts in regard to 

 the structure. Xo e\'idence of twins can be found. 



The rhombohedra of (laniet occur, without exception, of a light 

 green colour (in the garnet-amphibolite the colour is deep brownish- 

 red, and the crystal becomes a magnetic bead before the blow-pipe). 

 Sometimes the crystals merely make up the external part, while 

 the centre is filled with cpiartz, and then the garnet-substance is full 

 of fissures proceeding from the contact point with the quartz ; rutile- 

 needles are found within the crvstal in'niost confused accunuilations, 

 suggestive at times of whirlwinds, and showers of needles occur 

 within the garnet-substance as in fig. -J-. I'l. II. The garnet is 

 equally distributed throughout the whole of the rock, so diitering, 



