1813.] Miner ah from Greenland. 103 



some pieces of rose-coloured quartz, and a variety similar to 

 that which occurs at Bere Alstone in pseudo crystals, but not 

 quite so fine in the grain. I did not observe any of the other 

 varieties of the quartz family, such as agate or chalcedony, if i 

 except some minute particles of carnelian found among granular 

 magnetic iron. 



Zircon 



Occurs in minute crystals imbedded in felspar along with, and 

 also implanted in, alianite, for which substance I originally 

 mistook it. It occurs in six-sided prisms terminated by pyramids 

 of four sides : it is of a very dark colour^ with smooth brilliant 

 surfaces. 



Garnet. 



This substance I found of a form which I have not seen else- 

 where : it is a regular octohedron, truncated on all the edges 

 and angles. The principal crystal measures an inch and a quarter 

 along the edge; it belongs to a group which had been imbedded 

 in sodalite, and accompanied with augite. I found another 

 variety of a dark olive-green colour, crystallized in the leucite 

 shape, and imbedded in bluish grey quartz; also the red trans- 

 parent variety, presenting the same form, and imbedded in a 

 compound of quartz and felspar; likewise in amorphous trans- 

 parent concretions, imbedded in coarse gneiss ; and, lastly, in 

 small transparent grains, of a brilliant red colour, imbedded 

 along with augite in snow-white granular felspar, forming one of 

 the most beautiful rocks I ever beheld. 



Felspar. 



Besides as an ing%:f/dient in different rocks, I found this 

 mineral separately, in great abundance, crystallized, laminated, 

 compact, and granular. Of ' the first, the most remarkable 

 variety is one that forms an ingredient in a species of trap. The 

 crystals were principally detached ; but some I found connected 

 with that rock, the base of which is of a very coarse grain. 

 They are so rude in their confirmation, so very coarse in their 

 texture, and so uneven on. the surface, that it was some tims 

 before I recognized them as crystals. They vary in size from 

 three inches in length to one, Vv^ith the other dimensions in 

 proportion, nearly equal to the felspar crystals in the coarsest 

 granite. The most distinct form is a four-sided rectangular 

 prism, acuminated by one plane, which measures with the two 

 opposite sides 99° 41' and 80° 19^ being the form imitaire^ fig, 80 

 of Haiiy. Some of these crystals are modified by the truncation of 

 the acute solid angles; the rest are principally macles ; but 

 are all so much defaced by attrition, that it is nearly impossible 



