330 GIESECKI) ON THE GEOLOGY OF GREENLAND. 



These layers of cryolite are situated v^ry near each other, only 

 separated by a small ridge of gneiss, of a thickness of 27 feet ; 

 both are washed at high water by the tide, and for the most part 

 exposed, the superincumbent gneiss having been removed. The 

 white cryolite, seen at a distance, presents the appearance of a 

 small layer of ice ; small detached fragments have acquired, from 

 decomposition, the shape of cubes. This mineral is called by the 

 Greenlanders Orsuksikscet^ from the word orksuk^ blubber, to 

 which it bears some resemblance. The same name is also given 

 by the natives to white calcareous spar. 



3. Mica-slate is likewise one of the most common rocks in 

 Greenland, and an inseparable companion of gneiss ; there are 

 very few instances where they are not found in the vicinity of 

 each other, and frequently in contact. Mica-slate forms in this 

 country a very extensive series of mountains, which never rise to 

 a considerable height, and appear generally to rest upon gneiss. 

 Mica-slate is frequently visible on the shores; and the gneiss 

 itself forms also very extensive beds in it at Disko Bay, where the 

 whitestone also occurs in beds. The Greenlandish mica-slate 

 abounds in mica ; it is generally thin-slaty, and only thick-slaty 

 when the quartz prevails. Sometimes it has an undulating aspect ; 

 but, when this is the case, it passes into primitive clay-slate. The 

 mica of this mica-slate is mostly greyish-black and pinchbeck- 

 brown, passing into brownish-black, seldom silver-white. Its 

 quartz is pearl-grey. It is sometimes mingled with nodules of 

 pearl-grey felspar, from the size of a pea to that of an orange, and 

 this gives it the appearance of gneiss ; but they may be easily and 

 accurately distinguished, as the mica-slate presents a surface 

 perfectly continuous, and easily separable in the direction of the 

 plates of the mica. The strata dip towards north-west. 



Mica-slate also occurs in beds in various parts of this country. 

 One of the most remarkable, most interesting, and most extensive, 

 is that in the firth of Kangerdluarsuk in the 61st degree of 

 latitude, in the district of Juliana-Hope. It extends about five miles 

 in length and four miles in breadth ; its thickness varies from 6 to 

 12 feet ; and it contains, besides felspar, which is its principal con- 

 stituent part, hornblende, augite, actinolite, sahlite, garnet, and 

 that new mineral which has been analysed by Dr. Thomson and 

 Professor Eckeberg, called sodalite. It is of pale apple-green, leek- 

 green, greenish-white, and pearl-grey colour ; partly massive, partly 

 crystallised. Another mineral, which has not been analysed, 

 occurs also with the sodalite : it is of a peach-blossom red and 

 purple-red colour. On the shore the underlying gneiss is visible 

 in several places. In the superincumbent mica-slate, graphite 

 ["granite " in original] is found, of very fine texture, partly in veins, 

 partly imbedded. Calcareous . spar and fluor occur in veins, both 

 of which are sometimes coated with a thin crust of chalcedony ; 

 also galena in small veins. Blue phosphate of iron, in detached 

 pieces, is found on the shores. The mica-slate is generally 

 decomposed and iron-shot, where the graphite is imbedded. In 

 the Firth of Arksut a bed of very fine granular limestone is found 

 in mica-slate, which resembles the Carrara marble. The beds 



