1813.] Minerals from Greenlaiid. iOl 



first expected. Without enteriEg into a detailed mineralogical 

 description of each variety, I shall now briefly enumerate the 

 minerals contained in this collection, mentioning only such 

 peculiarities as appeared to me interesting, or that have hitherto 

 escaped notice. 



Cryolite, 



It is somewhat remarkable that on its first introduction into 

 Europe, this mineral met with the fate it so narrowly escaped in 

 this country. It has so strong a resemblance to some of the 

 most common fossils, that when received at Copenhagen it was 

 thrown aside as sulphate of barytes, and remained neglected for 

 some years. Its inferior specific gravity at last attracted the 

 notice of Abildgaard, who detected the presence of fluoric acid 

 and alumine in its composition , the former of which had till 

 then only been met with in combination with lime. The subse- 

 quent investigations of Klaproih and Vauquelln have given us 

 the analysis of this stone in a more perfect form. Besides 

 fluoric acid and alumine, they found soda, forming about one- 

 third ot the whole ; thus adding to the catalogue of minerals 

 the most interesting compound the kingdom affords. The name 

 which was given to it by Abildgaard, was suggested by its won- 

 derful fusibility, in which respect it surpasses every other 

 mineral. When in a pure state the colour is milk white, and 

 from its transparency it sometimes presents a greyish tinge, 

 particularly after immersion in water. I found it also of a 

 brown colour, occasioned by an admixture of ferruginous matter, 

 an accidental or mec hanical combination, in which it had not 

 been previously known : neither had it been described as being 

 accompanied by any other substance, although I now found it 

 along with sparry iron ore, galena, pyrites, quartz, and felspar. 

 Of these the first was the most abundant, and occurred in large 

 groupes of crystals tv»'o inches in length and one in breadth. In 

 the interior of some of them I observed minute transparent 

 crystals; but in general they are of a deep blackish brown, and 

 very much tarnished : some rhombs I found detached and inri- 

 bedded in the cryolite. 



Although there were several masses accompanied with galena 

 disseminated, there was only one specimen in v^^hich this mineral 

 was crystallized : in this it presented a cube of about half an 

 inch. The pyrites was likewise disseminated and crystaiiizedj in 

 the form of a cubo-dodecahedron. The quartz and felspar occurred 

 in imbedded crystals. Hence all the substances which I found 

 accompanying cryolite are crystallized ; but I could discover no 

 trace of any such arrangement in the substance itself, excepting 

 in its threefold cleavage. Among all the other stones of which 

 the collection consisted, I observed only two specimens accom- 



