x 
On Sodalite? 305 
by Haiiy, that fettstcin had been at first considered as a va- 
riety of (Vernerite. For the specimen sent to Mr. Allan, 
under the name of Compact Wernerite, is obviously the 
very'same with the supposed natrolite of Sweden. Now, 
- if. this identity be admitted, it will follow, that our mineral 
constitutes a species apart. It bears, indeed, a consider- 
able resemblance to it; but neither the crystalline form, 
nor the constituents of fettstein, as stated by Haiiy, are 
similar to those of the mineral to which I have given the 
name of Sodalite. The constituents of fettstein, as ascefe 
tained by Vauquelin, are as follows: 
Slit sche sspensicea =. eev. 44500 
iMuming. .eomiiag a. lo. evn) 34200 
Quiderotjbones 95, LA sisi. hh 400 
BORE hag! O9, S80 02M, BOL TN 1 
Potash and seda ............ 16°50 
OSs tae Cosa d . . «Mien? frat eB 
Uc 100°00 
II, Description of Sodaliie. 
Sodalite, as has been already mentioned, occurs in a pris 
mitive rock, mixed with sahlite, augite*, hornblende, and 
‘garnet fT. 
dt occurs massive; and crystallized, in rhomboidal dode- 
cahedrons, which, in some cases, are lengthened, forming 
six-sided prisms, terminated by trihedral pyramids. 
Its colour is intermediate between celandine and moun- 
tain green, varying in intensity in different specimens. In 
some cases it seems intimately mixed with particles.of sahi+ 
lite, which doubtless modify the colour. 
External lustre glimmering, internal shining, in one di- 
rection vitreous, in another resinous. 
Fracture foliated, with at least a double cleavage; cross 
fracture conchoidal. 
_ Fragments indeterminate; usually sharp-edged. 
Translucent. 
Hardness equal to that of feldspar. Tron scratches it 
with difficulty. 
Brittle. : 
Easily frangible. , 
1 : 
% This situation of the augite deserves attention. Hitherto it has-been, 
with a few exceptions, found.only in fletz trap rocks. 
+ The particular colour and appearance of this garnet, shows that the 
rock came from Greenland: for similar garnet has never been observed, 
ee in specimens from Greenland. 
ol, 37. No. 156. April 1811, U Specific 
