Ago AVALTSIS OF SODALITE. 



werneritpjifir obviously the very same witli the supposed ria- 

 trolite oi' Sweden. Now, if this identity be admitted, it wiTt 

 follow, that our mineral constitutes a species apart. It bears, 

 indeed, a coasideiable rtseu»t)ldn« e to il ; but neither the 

 ^trystaUiue foriu, nor the consbtiients of fettsteio, as siated by 

 Haiiy, are bvniiiar to those of tlie mineral to which I have 

 given the name of sodalite. The constituents of fett»tein, 

 «» ascertained by Vauquelin, are as follows: 



Constituents of Silica*..... •••44*00 



Alurnin**. 34*00 



Oxide of iron "^ 4*00 



Lime ....... w .i •'•••*•••*'•'*... ... 0*12 



Potash and soda* ••*•••• ......•• l6*50 



Loss ••>. 1-38 



100*00 



I^escnption ol ^ §odalite, as has been already mentioned, occurs in a pri- 

 soUalite, mitive rock, mixed with sahlite, augite*, hornblende, and 



garnet t* 



It occurs massive ;j|nd crystallised, in rhomboidal dodeca- 

 hedrons, which, in some cases, are lengthened, forming six- 

 lided prissms, terminated by trihedral pyramicis. 

 **vlt« colour is intermediate between celandine and moun- 

 tain green, varying in intensity in different specimens. In 

 Bome cases it seems intimately mixed with particles of sah- 

 lite, which doubtless modify the colour. 

 ' '. i. External lustre glimmering, internal shining, in one di- 

 -jre^tion vitreous, in another retinous. 



Fracture foliated, with at least a double cleavage ; cross 

 -fracture conchoidril. 



J, Fragments irtdetecminate ; usually sharp-edged. 

 Translucent. 



Hardness equal to that of felspar. Iron scratches itwith 

 difficulty. 



• This situation qf ihe augite fleserf es attention. Hitherto it has been, 

 vlth a few exceptions, found only in flatz trap roCks. 



f Tlje particular colour and appearance of this garnet shows, that the 

 rock came from. Greenland : for similar garnet has irever been observed, 

 except in apeiimens from Grceftliftd, ■ 



Brittle. 



