Sketch of the Mine of Pasco. 45 
pasty state ; the quicksilver being afterwards expelled by heat. It 
corresponds with no natural form that I have ever seen. 
5. Specimens that are softer and more sectile than the native sil- 
ver 3 apparently composed of little plates, that seem by compression 
to slide over each other, like amalgam. 
6. Numerous specimens of sulphuret of silver, which, from the 
proportion they bear to the whole collection, would seem to be 
the most common product of the mines. The color of this ore is 
dark gray 3 structure granular, or perfectly foliated; streak brilliant ; 
sectile, cutting with a knife, almost like lead, and more lke plumbago, 
to the brilliant specimens of which, it often bears a strong resem- 
blance, but it does not mark paper. It is in some pieces mixed with 
finely divided native silver, so that when cut, the peculiar color of 
both is displayed. The tarnished, dull specimens are brilliant, if cut. 
By the blow pipe, it is reduced to the condition of metallic silver, 
the sulphur being exhaled in fumes, and escaping with ebullition, 
which throws the silver about in jets, and on cooling, it appears on 
the charcoal, in brilliant white points. If the process be stopped be- 
fore the reduction is thoroughly accomplished, the globule, on cool- 
ing, exhibits a beautifully mottled appearance, not unlike that of the 
variegated soap balls. It is produced by the congealed silver, being 
interspersed, with its characteristic whiteness, in lines, clouds, and 
spots, inthe dark base, of that part of the sulphuret, which is still un- 
reduced. — 
7. There is one mass of sulphuret of silver, which is distinguished 
from all the others by its beauty ; it is in large brilliant plates, having 
almost the lustre of polished steel, but the color of the darkest plum- 
bago. Its size is four inches long, two and a half wide, and two 
deep. This also gave metallic silver by the blow pipe. 
8. There are large masses of what appears to be muriate of sil- 
ver, soiled by and mixed with an ochreous powdery earth. Still, 
the masses are tolerably firm, and it is only by breaking them that 
the muriate is discovered, in laminated veins of a light gray color, 
brittle, and giving points* of reduced silver, by the blow pipe. 
9. Most of the foreign substances observed with these specimens 
are calcareous ; sometimes the native silver was interspersed in quartz, 
but more frequently in cale spar. 
* Points, because there is earthy matter mixed with it, which gives only a slag, 
