CRYSTALLISED GADOLINITE. — — 35 
THE arrangement of BRONGNIART appears much more ju- 
dicious; he has placed it at the commencement of the Earthy 
Minerals, and aflighs as a reafon, that it is unique in its com- 
pofition ; and if placed in any other fituation, it would interrupt 
the feries, either in refpedt to its compofition or external cha- 
racters. 
Or the Cryolite I have very little to obferve, in addition to the 
defcriptions given in the different mineralogical works. The 
fpecific gravity I found to be 2.961; Haiiy ftates it at 2.949. 
Among the various mafles I examined, there was no trace of 
cryftallization, farther than the cleavage, which is threefold, 
and nearly at right angles. The mafles broke in two direc- 
tions, (which may be fuppofed the fides of the prifm), with. 
great facility, leaving a very fmooth furface ; but the tranfverfe 
cleavage was more difficult, and by no means fo {mooth. Se- 
veral of the fpecimens being mixed with galena, pyrites, and. 
cryftals of {parry iron-ore, it would appear that the cryolite is 
a vein-ftone ; but I was not fo fortunate as to find any of it at- 
tached to a rock fpecimen, fo as to throw light on its geo- 
gnoftic relations. 
