AN ACCOUNT OF THE CRYOLITE OF GREENLAND. 



COMMUNICATED BY MESSRS. LEWIS & SONS. 



[Messrs. Lewis & Sons, of Philadelphia, the proprietors of the mine of cryolite 

 described in the following article, have kindly supplied the Institution with a 

 quantity of the mineral for the distribution of specimens to such institutions as 

 may desire to add it to their cabinets. The Institution is also indebted to the 

 same gentlemen for the account here given and a large map which accompanied it. 



The mineral cryolite derives its name (from xpooq, ice) from its property of 

 melting in the flame of a candle. Its composition is Na. FI.|^ Al.^ ri.^=x Alu- 

 minum 13.0 ; sodium 32.8 ; fluorine 54.2. 



It is valuable as an ore of aluminum, for when melted with sodium this metal 

 is liberated from its combination with fluoiine, the result being aluminum and 

 fluoride of sodium. 



Since the high price of sodium restricts the useful applications of aluminum 

 and its alloys, cryolite has lately become important as a source of soda, consid- 

 erable quantities of which, with alumina as an incidental product, are manufac- 

 tured in Pennsylvania from this mineral.] 



Copenhagen, November 15, 1864. 



GrBNTLEMEN : After staying a year at the cryolite mines, the nature of which 

 I have thus had good opportunity of learning, I can give you the following 

 information about them, as they were at the time of my departure in the autumn 

 of 1864. 



The cryolite mines are situated at Trigtut, (or Triktout,) on the south side of 

 Arsut Fjord, in South Grreenland, 61° 13' north latitude and 48° 9' west longi- 

 tude. The surface of the vein of cryolite was originally covered with a layer 

 of clay, gravel and earth, which loose material is now chiefly removed, there 

 remaining only in the most southern part of the area of cryolite, a part not yet 

 perfectly uncovered. The boundaries of the vein toward the surrounding 

 mountain is everywhere very conspicuous, with the exception of a part of its 

 northwest side. 



The vein, the greatest length of which is about 600 feet, breadth about 150 

 feet, and extent of which can be reckoned at about 53,000 cubic feet, is of 

 two parts, one close to the Fjord, the other to the east, and separated by a rock 

 from 5 to 15 feet high and about 100 feet broad. The western part is washed 

 by a little bay going in from the Fjord along its whole extent ; this is now 

 partly filled up, and will in time be perfectly separated from the sea, when the 

 stone breakwater, now under construction, running in west-southwest and east- 

 northeast direction, straight across the mouth of the bay, at a distance of about 

 250 feet from the cryolite mine, is finished, and when the whole of the bay in- 

 side the breakwater is filled up, which two works will in all probability be 

 finished before the close of 1865. The rock bounding the vein is everywhere on 

 the boundary line itself 10 to 15 feet high from west, and the south boundary 

 rises tolerably quickly in towards land. The surrounding elevation is chiefly 

 of granite, crossed in several parts by veins or layers running from northwest 

 to south. 



The principal mineral of the vein is, of course, the cryolite,^ but as constai; 



