374 On Metallic Minerals. 



It contains specks of iron pyrites, as indeed does most of the 

 ore from lience, it being under the form of sulphuret of 

 iron, that the sulphur is present in the bed. Its structure 

 is fine-grained, and fracture uneven ; lustre, glimmering 

 metallic; yields to the knife; powder, bluish black; no 

 change in nitric acid j specific gravity, 4-3 ; magnetic, 

 &c. &c. 



4th. — This is like No. 3 in most respects ; the form under 

 which it occurs is, however, different. It is found in 

 parallel layers with rusty surfaces between them. Its 

 rectangular outline and steel grey lustre gives it the 

 appearance of a piece of manufactured iron — specific 

 gravity, 4-6. Mr. Manahan has observed that where 

 fragments of ores are found of regular forms, they are sure 

 to be of good quality. 



5th. — Occurs as a cellular crust upon some of the other 

 ores, from one-eighth to one-half of an inch in thickness. 

 Colour, bluish black; opaque; structure, cellular and 

 platy, the interstices between the plates forming the cells; 

 fracture, uneven ; lustre, pitchy and glistening ; yields to 

 the knife; very brittle; powder, snuff colour; specific 

 gravity, 2-8; no change in nitric acid ; magnetic, &c. &c. 



The large masses of crystalline epidote which are found 

 here, deserve some description, but I fear that the little 

 acquaintance I possess of the crystallographic characters of 

 minerals, will render it a very imperfect one. 



Colour, a greyish or yellowish green ; translucent on the 

 edges. It occurs in masses composed of an assemblage of 

 large crystals, crossing each other without order or regu- 

 larity ; these crystals appear to be four-sided oblique 

 prisms. Fracture, uneven ; lustre, between glistening and 

 glimmering — some faces of the prisms have a shining lustre. 



I 



