SODALITE AT SALEM, MASS. 5 



The composition of sodalite, calculated from the formula 

 ;iven on the preceding page is as follows : 



3Na 0, 93 = 18.98 

 3Ab 3 , 153.78 = 31.38 

 6Si0 2 , 184.86 = 37.72 

 Na, 23 = 4.69 



CI, 35.46 = 7.23 



490.10 100.00 



with this the results obtained by analysis agree quite closely. 

 It is worthy of note, that although the specimen employed 

 was unusually deep coloured, scarcely appreciable traces of 

 iron were detected; the alumina thrown down from its solution 

 in aquaregia was white, and most of the reagents for iron gave 

 negative results ; it is therefore very doubtful if this mineral 

 owes its color to iron, as has been supposed. 



ElcBolite The elasolite of this locality is filled with minute 

 specks, probably mica or feldspar, from which it cannot be 

 separated mechanically ; this impurity amounts to about 3 per 

 cent., and remains behind when the levigated mineral is dissolv- 

 ed in acids. The elteolite occurs in compact masses, of a light 

 green colour and greasy lustre ; in connection with orthoclase 

 it forms the bulk of the vein; it has not yet been observed in 

 crystals. Heated before the blowpipe it fuses and gives off a little 

 moisture. Dried at about 150° C. it has the following com- 

 position : 



Silicic Acid 44.32 



Alumina 32 69 



Soda 17.02 



Potassa 5. 09 



Lime 59 



99.71 

 It also contains slight traces of iron. A portion dried at 100° 

 C. and then ignited lost 1.31 per cent. 



The sodalite is found near the centre of the vein in thin lay- 

 ers. There is no doubt that this locality will furnish fine cabi- 

 net "specimens when more deeply explored. As the vein strikes 

 dowmvard at a very acute angle, extensive blasting will be 

 necessary ; however it well deserves a thorough exploration, for, 



