Geology. 433 
as illustrative of the age of this important metal, mention 
that of native silver, and several of the most important 
ores. ' 
cl* Natwe Silver . — It occurs, with the exception of 
slight traces in the well-known corn-ears of Hessia, in 
fixtz -mountains, always in, veins that traverse primitive 
and transition mountains. It appears in veins that trav 
verse granite in Suabia, and sometimes in Saxony ; in 
vein 3 that traverse gneiss and mica-slate in Saxony, Bo- 
ft, arid Norway; in veins that traverse clay- slate in 
b .,id Bohemia ; and, lastly, in veins that traverse 
, rpiiyry and sienite, in Saxony and Hungary. The age 
A the rock, however, does not always correspond to that 
of the venigenous formation ; thus, the veins in the gra- 
nite of Furstenberg are newer than those in some of the 
varieties of Saxon gneiss. It occurs in very inconsidera- 
ble quantity in transition-mountains. 
b . Antimonial Silver . — It occurs only in veins. In 
Wirtemberg, these veins traverse granite, and in the 
Harfcz, grey-wacke ; nevertheless, these formations do not 
differ much from each other. 
c. Corneous Silver-ore , Muriat of Silver of chemists. 
This remarkable ore of silver occurs always in silver 
| veins, but only in their upper part, and in such a position 
in regard to its accompanying minerals as shews that it 
is always the newest fossil of the vein in tvhich it appears. 
These veins traverse granite, gneiss, mica-slate, and clay- 
slate.* It occurs only, in quantity, in Mexico and Peru : 
small portions have been observed in Saxony, Cornwall, 
Siberia, and other countries. f 
II 
* It is said to occur in floetz-limestone in Peru. 
1 
| This ore particularly the conchoidal subspecies, has an icy 
glassy aspect, and hence was denominated Vitreous or Glassy Sil- 
f ver-ore by older mineralogists. The vitreous sii ver-ore of Kir- 
