290 Messrs. Jackson and Alger on the 
red oxide of copper, which are translucent and of a crimson 
red color. 
Green and blue carbonates of copper occur, investing some of 
the lignites ; and, filling interstices in the sandstone, they assume 
a botryoidal appearance. They also occur in delicate fibres, 
investing the masses of vitreous copper ore now to be described. 
This valuable ore occurs in beds from two to four inches 
thick, which, covered with lignites, alternate with each other, the 
lowest bed being the thickest and most compact. It is of an iron- 
black color, with a slight tinge of lead-grey. It possesses a 
metallic lustre, and breaks with a conchoidal fracture. Some 
specimens are of a crystalline or granular structure, breaking so 
as to exhibit brilliant metalloidal surfaces ; others are very com- 
pact, and break with a smooth surface. The specific gravity of 
the most compact variety is 5.7; but the granular varieties, 
more open in their texture, seldom exceed 4.8 or 5. It is sec- 
tile, and readily impressed by a smooth, blunt steel instrument ; 
it therefore possesses a low degree of malleability, being extend- 
ed under pressure without breaking. It receives a high polish, 
resembling in lustre and color the most highly polished steel, 
and retains this lustre unaltered by the action of the atmo- 
sphere. It is mixed occasionally with yellowish and a lighter 
grey pyrites, which is much harder and not sectile,and con- 
tains a smaller proportion of copper than of iron ; but no 
specimen of this ore gives any traces of arsenic or antimony, 
when examined before the blowpipe, or when dissolved in nitro- 
muriatic acid and largely diluted with water. Nor does a solu- 
tion in nitric acid give any precipitate when muriate of soda is 
added; and sulphuric acid throws down no precipitate ; hence 
it does not contain any silver or lead. The nitric solution, tested 
