TAYLER ON THE CRYOLITE OF GREENLAND. 345 



By reference to the horizontal section (fig. 1), two trap-veins 

 will be seen bounding a space containing the Cryolite and the 



minerals accompying it. 



To this space I shall con- 

 fine my remarks. The 

 section is not drawn accu- 

 rately to a scale, but it is 

 about ^^ inch to the fathom. 

 Starting from the western 

 trap-vein, which is situated 

 in schistose gneiss and 

 hornblende schist, we find 

 the gneiss gradually losing 

 its slaty structure, until in 

 the neighbourhood of the 

 cryolite it becomes granitic, 

 and now contains numer- 

 ous metallic traces. Before 

 arriving at the cryolite 

 we find a wide vein of 

 white quartz and felspar 

 running about S.W. ; the 

 quartz and felspar are in 

 very large masses and 

 crystals, some crystals of 

 quartz measuring a foot in 

 thickness. This rock is 

 traversed in several direc- 

 tions by small veins and 

 masses of cryolite, isolated 

 from the larger body of 

 that mineral, in which, as 

 well as in the rock, are to 

 be found numerous crystals 

 of a variety of tantalite, 

 oxide of tin, blende, molyb- 

 denum, much galena, cop- 

 per pyrites, arsenical and 

 iron pyrites, and sparry 

 iron ore. In this rock are 

 many small caverns, arising 

 from the decomposition of 

 the felspar, and probably 

 also from the decomposi- 

 tion of the cryolite, which 

 is here porphyritic, con- 

 taining crystals of felspar 

 and quartz. The floors of 

 these caverns are covered 

 with loose crystals and 

 fragments of felspar, and in 

 some places kaolin, crystals 



