3^ 



l'KNTTI KSKOI.A. M.-N. Kl. 



the solution was brought to the sp. g. 3.35, and what now sank down was 

 purified further and used lor an analysis that was made by Mr. L. Thomas- 

 sen with ilie following result: 



The optical character is positive, and the axial angle is larger than 

 in common diopside. I measured with Klein's lens 2 E = 149', from 

 which 2 V = 82 ' 40 . 



Dispersion of the optic axes is strong, p ^ v, and it is stronger in 

 axis A than in axis B. Sections nearly perpendicular to the optic axes 

 show abnormal lavender-blue interference colours. 



S. Franchi found the dispersion in chloromelanitic pyroxenes to rise 

 with the quantity of ferric oxide'. The present p^TOxene, containing 

 5.62 ^/0 FegOg, seems to confirm his conclusion. 



The mineral is megascopically very dark green and, in thin sections, 

 shows a beautiful intense green tint that would suggest the presence of 

 chromium. The chemical test, however, proved chromium to be absent. 

 Pleochroism is almost imperceptible: the colour for ß appears to be a little 

 deeper green than for a and y. 



The intense green colour apparently may be ascribed to the presence 

 of the large amounts of aegirite, but the present pyroxene differs from the 

 latter in the absence of pleochroism, probablv due to the predominance of 

 the Jadeite. 



' S. Franchi, Sulla dispersione nei pirosseni cloromelanitici di alciini roccie cristalline delle 

 Alpi occidendali. BoU. Comm. geol. d'Italia. 1901, N:o 4. 



