114 Native Copper, Ores of Copper, and other Minerals. 



Mountain Leather. — A variety of this mineral, which from 

 its resemblance to horn, might be properly enough called tnoun- 

 tain horn, occurs in thin plates, associated with the native copper 

 and the oxide of copper at New Brunswick. It has a gray or 

 bluish white color, is composed of fibres, brittle, imbibes water, 

 and then becomes apparently more tender. 



Small fragments alone, before the blowpipe curl up, and if the 

 heat is continued, melt into a white enamel or opaque glass. 

 These characters sufficiently distinguish this mineral from Abes- 

 tus, and from the Nemalite of Nuttall, to which it bears some re- 

 semblance. 



I have also found in this vicinity, masses of the same mineral 

 of a more spongy texture, scarcely fibrous, and of a lighter color. 

 They resemble decayed wood. Their behavior before the blow- 

 pipe, is similar to that of the preceding variety. 



Bitumen. — About two miles northeast of Somerville, there is 

 found in cavities in the slate rock, a variety of bitumen, which de- 

 serves to be noticed. It has the consistence of wax, and is of a black 

 or dark brown color. When heated to redness on a piece of pla- 

 tina foil, it burns with a yellow flame, emits a dense smoke, and 

 leaves a slight coaky residuum. It approaches more nearly to 

 the variety, called elastic bitumen, than any other, but it is softer 

 and is not elastic. My specimens have undergone no change in 

 the three or four years in which they have been in my possession. 

 I make this remark because it has been stated, that the soft elastic 

 bitumen, by long keeping, becomes hard and brittle. The min- 

 erals of organic origin, allied to the one just noticed, have re- 

 cently been examined by Professor J. F. W. Johnston, and by 

 his able investigations, our knowledge of them has been greatly 

 extended. I regret, that the small quantity of this substance in 

 my possession prevented me from determining its other chemical 

 characters. 



