88 B. KOTÖ. 



Such an assumption is, as it seems to me, precarious ; for, the writer 



has observed the same phenomenon in the pargasite from Pargas, 



Finnland, especially on the periphery, where the Finnish mineral 



shows a slight inclination to transformation. Even in the central 



intact part such green spots are by no means rare. 



The orthopinacoid of our glaucophane extinguishes the light, 

 t 

 of course, parallel to C, and also at ± to it ; but the shade sweeps over 



the section in an undulating manner as we rotate the table. Owing 



to this fact, the direction of extinction might easily be mistaken for an 



oblique one with a small angle. 



Taken as a whole, the crystal-individuals of our glaucophane 

 possess a broad columnar form whose basal section presents an elong- 

 ated rhombic outline, truncated at the acute corners by traces of the 

 clinopinacoid ; (/^. 11^ and are terminated at both ends by an 

 orthodome or hemi-pyramid. The axial colour : G = greenish blue; 

 B = lavender blue ; Ä ■= bluish brown. C > B > A. 



This mineral has been isolated from other constituents of the 

 schist by the Thoulet solution, and the analytical result obtained by 

 Mr. Yoshida,* is as follows : — 



Si Oa 56, n 



AkOa 15, 14 



Fe, O3 9, 78 



Fe 4, 31 



Ca 4,80 



MgO 4,33 



Ncio^O 4,83 



7C 0, 25 



100, 15 Sp. Gr. = 2, 9912 



* I gladly take this opportunity of returuiug my hearty thauks to him for the chemical 

 analysis of this mineral. 



