TRANSACTIONS OF THE SECTIONS. 53 



being taken to insure accurate results, and the compos-ition obtained 



was as follows : 



Silica 38*75 contained 20*130 oxygen. 



Alumina 17*35 8*102 "j 



Protox. iron 8*10 ■ 1*8431 >19*979, 



Lime 33*60 9*436 > 11 -859 J 



Magnesia 1*50 *580j 



99*30 

 which is most accurately represented by the formula, 



7 (FO CaO MgO)3 Silg + 5 AIX),, SiOg. 



2. Specimen from Slatoush in Siberia. 



Colour light yellow-green ; vitreous lustre ; streak white ; graimlar 

 composition, and the individuals slightly connected, semi-transparent. 

 The result of the analysis approaches very closely that of magnus and 

 turrenkass, and differs completely from that of Mr. Ivanoe. It con- 

 tained as follows : 



Silica 37*45 contained 19*454 oxygen. 



Alumina 18*85 8*662"] 



Protox. iron 7*75 1*7641 > 20*849, 



Protox. manganese Lw-ir'tJ 



Lime 35*25 9*901 f ^^^^^ 



Magnesia 1*35 *522j 



100*35 

 which may be represented by the same formula as the above. 



3. Specimen from Piedmont. 



Colour sage-green ; vitreous lustre ; semi-transparent ; in part mas- 

 sive, terminating in small crystals ; fracture uneven. The result of 

 the analysis was. 



Silica 39*25 containing 20*390 oxygen. 



Alumina 17*30 8*079 



Protox. iron 7*62 

 Protox. man. 3*50 

 Lime 32*25 



Magnesia *47 



11*823 



} 



19*902. 



100*39 

 This also corresponds with the former. 



4. Specimen of Vesuvianfrom Monte Somma. 

 It possessed the following characters : colour olive-green ; lustre 



