390 On SODJLITE, a new 



as Hated by Hauy, are fimilar to thofeof the mineral to which 

 I have given the name of Sodalite. The constituents of fetts- 

 fiein, as afcertained by Vauquelin, are as follows : 



Silica, - 44.00 



Alumina, - - 34«oo 



Oxide of iron, - - 4.00 



Lime, - - - 0.12 



Potafh and foda, - - 16.50 



Lofs, - - - 1.38 



100.00 



II. Description of sodalite. 



Sodalite, as has been already mentioned, occurs in a pri- 

 mitive rock, mixed with fahlite, augite *, hornblende, and gar- 

 net f* 



It occurs mafllve ; and cryftallifed, in rhomboidal dodecahe- 

 drons, which, in fome cafes, are lengthened, forming fix-fided 

 prifms, terminated by trihedral pyramids. 



Its colour is intermediate between celandine and mountain 

 green, varying in intenfity in different fpecimens. In fome 

 cafes it feems intimately mixed with particles of fahlite, which 

 doubtlefs modify the colour. 



External luftre glimmering, internal mining, in one direc- 

 tion vitreous, in another refmous. 



Fracture foliated, with at leafl a double cleavage 5 crofs 

 fracrare conchoidal. 



Fragments indeterminate ; ufually fharp-edged. 



Translucent. 



*~This iltuation of the augite deferves attention. Hitherto it has been, 

 with a few exceptions, found only in flretz. trap rocks. 



f The particular colour and appearance of this garnet, /hews that the rock 

 came from Greenland : For fimilar garnet has never been obferved, except in 

 fpecimens from Greenland. 



