346 On h MINERAL supposed to be 



had been brought ; the only Cryolite known in Europe having 

 been fent by a Miflionary from Greenland to Copenhagen. 



The 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- 

 fcription. I was led to fufpect 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 affigned 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 investigation, however, furnifhed a 

 ftrong proof of the fuperiority of chemical teft over external 

 character ', for although the fhape, luftre, fracture, 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 ntmofl 

 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 differed fo very widely 

 from thofe I was taught to expect. 



It is more than twenty years fince the gadolinite was firft 

 obferved by M. Arrhenius, in an old quarry at Roflagie, near 

 Ytterby in Sweden. It was defcribed by Mr Geyer, and by 

 him conftdered as a black zeolite. 



In 



