44 Sketch of the Mine of Pasco. 
years, established as a merchant at Lima, has availed himself of his 
opportunities, to make various collections, interesting to the fine and 
useful arts, particularly of numerous and valuable pictures, and also 
of noble native specimens of silver, which he has brought home. The 
box containing them, being left in trust with me, during the absence of 
its owner in Europe ; I have, with permission, examined its contents 
with some attention, and a brief notice of them seems not an inap- 
propriate introduction to the Memoir of Mr. Rivero. 
1. Among the numerous pieces of native silver, there is one pure 
and solid piece, without pores or intermixture. It is seven inches 
long, five and a half broad, and from three to two and a quarter thick. 
Its weight exceeds fourteen pounds avoirdupois, and its value, as 
silver merely, is over two hundred and thirty dollars. It is from‘ the 
_ mines of Pasco, and appears to be a fine exhibition of the full dimen- 
sions of a rich vein or cavity of virgin silver, as it has the natural 
faces by which it was joined to the rock or vein stone, (a calcareous 
one as appears by very small adhering portions.) On one side only, 
does it bear marks of having been cut and forced by instruments 
from the rest of the vein. It exhibits the appearance of having been 
a knob or protuberance. 
2. There are other pieces of native silyer, from the size of a hand 
to that of a walnut, in many accidental and imitative forms ; protu- 
berant, dendritic, cellular, pectinated, reticular, &c. 
3. Two specimens are worthy of being mentioned, on account of 
the beauty of their crystallization; especially as good erystals are 
much more frequent among the ores, properly so called, than among 
the native metals. 
In these pieces, which are from two and a quarter to three and a 
half inches in length, the silver is of the most perfect whiteness, 
without tarnish, and with the lustre of the polished metal; and the 
numerous crystals, both adhering in rich groups of many hundreds, 
and being also interspersed through brilliant white cale spar, make a 
very splendid appearance. The figures are between the cube and 
octohedron,—usually the cubo octohedron. The forms of the crys- 
tals are‘not readily distinguished, without a magnifier. 
4. An elliptical ovoidal mass, four and a half inches long by three 
and a half wide, and two and a half deep, nearly flat on one side. 
It is porous in every part, and has the appearance of having been 
produced by amalgamation, and of having been moulded, while in a 
