346 On a2 MINERAL supposed to be 
had been brought ; the only,Cryolite known in Europe having 
been fent by a Miflionary from Greenland to-Copenhagen. 
Tne Gadolinite, from its extreme fcarcity, is a mineral 
to be found in very few cabinets; and when this collection 
fell into my hands, was one of ‘thofe I knew only by de- 
{cription. I was led to fufpeét that fome of the minerals 
in this parcel belonged to that fpecies, by obferving, im- 
bedded in a piece of granite, fome fmall fhapelefs mafles, 
whofe external characters appeared to correfpond entirely with 
thofe afligned to the gadolinite ; but on reference to the mi- 
neralogical works which treat of this ftone, I found more diffi- 
culty than could have been fuppofed in afcertaining whether 
they did fo or not. The inveftigation, however, furnifhed a 
ftrong proof of the fuperiority of chemical teft over external 
character; for although the fhape, luftre, fra@ture, and geogno- 
ftic relations, left me fcarcely any room to doubt, yet on apply- 
ing the blow-pipe and acids, it was quite evident, that the ftone 
I firft tried could not be gadolinite. I examined with great care 
the reft of the parcel, and picked out feveral, which, though very 
different, refembled in various refpects the one that originally at- 
tracted attention; and with a view to fatisfy myfelf, I fent 
duplicates to a friend in London, from whom I learnt, that 
one of thofe which I fuppofed to be gadolinite was certain- 
ly that mineral. Notwithftanding the very refpectable autho- _ 
rity I had obtained, to which I was inclined to pay the utmoft 
deference, it was not till after minute and repeated inveftiga- 
tions that I found myfelf difpofed to fubmit to it; the phyfical 
characters of the fpecimen in queftion SHEETS, fo very widely 
from thofe I was taught to expect. 
Ir is more than twenty years fince the gadolinite was firtt 
obferved by M. ARRHENIUS, in an old quarry at Roflagie, near 
Ytterby in Sweden. It was defcribed by Mr Geyer, and by 
him confidered as a black zeolite. 
In 
