SILVER. 
493 
times branched, occasionally in capillary filaments, 
and not uncommonly in leaves. Thus it appears in 
most mines, and particularly in those of Siberia, 
where Patrin tells us he never met with it crystal- 
lized. It is found in the mines of Peru in a vece- 
table form, imitating the leaves of fern. This 
pretty variety of figure in native silver is occa- 
sioned by a vast number of little eight-sided cry- 
stals, so disposed upon each other as to give the 
whole the appearance of a vegetable. The curved 
cylindrical filaments, in which form silver is some- 
times found, are of various sizes, from the thickness 
of a finder to the diminutive size of a hair. It is 
O 
very rare to find it in separate cubical or octaedral 
crystals. Rome de lisle speaks of a specimen in 
which the crystals where as large as a filberd, having 
the form of a cube, of which the eight solid angles 
were truncated. This piece came from the mines of 
Konigsberg in Norway, and was imbedded in white 
calcareous spar. 
Native silver is seldom found pure, but is gene- 
rally mixed with other metals ; such as gold, cop- 
per, mercury, iron, lead, &c. This last metal al- 
most always contains a portion of silver, though fre- 
quently so small as not to be worth the expense of 
separating it. In the reign of Edward the First 
near lboo pounds weight of silver were obtained, in 
the course of three years, from a mine in Devon- 
shire, which had been discovered about the year 
900 . The lead-mines in Cardiganshire have, at 
different periods, afforded great quantities of silver. 
