144 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Jan. 23, 



cryolite ; it probably extends to a great depth, and exists in great 

 quantity. 



The fact of its solitary occurrence in this spot induces speculation 

 in regard to its origin. The number of minerals, mostly crystallized, 

 which accompany it, indicate some powerful • and long-continued 

 agency to have operated in a limited space. The few facts I have 

 stated may suggest some opinions which may elucidate the as yet ill- 

 understood subject of mineral veins. The cryolite has been hitherto 

 applied to few purposes. The Greenlanders were the first to turn it 

 to account, which they did in a curious manner, viz. the manufacture ' 

 of snuif. They grind the tobacco-leaf between two pieces of cryolite, 

 and the snuff so prepared contains about half its weight of cryolite 

 powder. This snuff they prefer to any other. In Europe cryolite 

 has been employed to a limited extent ; but the recent discovery of 

 the mode of preparing aluminium will probably render it a valuable 

 ore of that metal. 



2. Description of Remarhahle Mineral Veins. 

 By Prof. D. T. Ansted, M.A., F.R.S., F.G.S. 



[This Memoir was preceded by an introduction, in which the author, 

 after certain definitions, stated the class of facts which he considered 

 it desirable should be recorded by mining engineers in investigating 

 mineral veins, in order that their observations might be available for 

 scientific purposes.] 



1. The Cohre (Copfer) Lode of Santiago de Cuba. 



As being a very exceptional and remarkable vein, and one which 

 possesses a remarkable geological interest, I have selected for this 

 memoir the great Cobre lode, and I propose to describe and, as far as 

 possible, explain the conditions of this vast deposit of mineral wealth.. 

 I select it with the greater readiness, as it has not hitherto, I believe, 

 been the subject of scientific investigation, although known for twenty 

 years as the richest copper lode which has within that period been 

 the object of continuous mining operations in any part of the world. 



Position of the Lode. — This deposit of copper ore, opened in a hill 

 near the small town of El Cobre, is about eight miles W.N. W. of the 

 town and magnificent harbour of Santiago de Cuba, the mines being 

 directly connected with the harbour by a railway, which takes ad- 

 vantage of the valley of the Cobre River to reach the mining district. 

 There is a fall of about 300 feet from the plateau on which the town 

 is built to the sea, and the hill on which the principal crop of the 

 lode takes place is about 300 feet above the level of the railway. 

 The line of railway running nearly parallel to the principal direction 

 of the sierras, both along the coast and in the interior, gives some 

 little insight into the structure of the country, and to the facts ob- 

 served in the cuttings I shall have occasion to allude presently. 



