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LIT. A Chemical Analysis of Sodalite, anew Mineral from 
Greenland. By THomas THomson, M.D. F.R.S.E. 
Fellow of the Imperial Chirurgo- -meilical Academy of 
|. Petersburgh*. 
Tae mineral to which I have given the name of sodalite 
was also put into my hands by Mr. Allan. In the Green- 
Jand collection which he purchased, there were several 
specimens of a rock, obviously primitive. In the compo- 
sition of these, the substance of which I am about to treat 
formed a constituent, and, at first appearance, was taken 
for feldspar, to which it bears a very striking resemblance. 
This rock is composed of no less than five different fossils, 
namely, garnet, hornblende, augite, aid two others, which 
form the paste of the mass. These are evidently different 
minerals ; but is some specimens are so intimately blended, 
that it required the skill of Count Bournon to make the 
discrimination, and ascertain their real nature. Even this 
distinguished mineralogist was at first deceived by the ex- 
ternal aspect, and considered the paste as common lainel- 
lated feldspar, of a greenish colour. But a peculiarity 
which presented itself to Mr, Allan, in one of the minerals, 
imduced him to call the attention of Count Bournon more 
particularly to its construction. 
On a closer examination of the miveral, M. de Bournoa 
found that some small fragments, which Pe had detached, 
presented rectangular prisms, terminated by planes, mea- 
suring, with the sides of the prism, 1102 and 70? or nearly 
so,—a form which belongs to a rare mineral, known by the 
name of Sahlite, from Sweden. He Susthee observed, in- 
termixed along with this, another material ; and after some 
trouble succeeded in detaching a mass, presenting a regular 
rhomboidal dodecahedron. It was to this form that Mr. 
Allan had previouly requested his attention. 
* Some time before this investigation, M. de Bournon had 
‘examined a mineral from Sweden, of a lamellated structure, 
and a greenish colour, which he found indicated the same 
form. From this circumstance, together with some ex- 
ternal resemblance, which struck him, he was induced to 
conclude that our mineral was a variety of that substance. 
To that substance the t.ame of Swedish nalrolite had 
been given, in consequence of the investigation of Dr. 
Wollaston, who found that it contained a large proportion 
of soda. 
* From the Transactions of the Royal Society of Edinburgh. 
There 
