338 
MINERALS. 
those beds in various directions, and almost always 
under a considerable angle. 
“ Metallic veins,” says M. Eller, “ are found 
only in elevated places in a long chain of moun- 
tains. This chain of mountains is always supported 
by a basis of hard rock. As long as this rock pre- 
serves its continuity, there is no chance of discover- 
ing metallic veins : but when vve meet with crevices 
or fissures, we then entertain hopes of finding metal. 
Mineralogists have remarked that, in Germany, the 
most favourable situation is when the mountains rise 
gradually, stretch towards the south-east, and, after 
attaining their greatest elevation, descend gently to- 
wards the north-west. 
« It is generally in a rugged rock,” continues 
M. Eller, “ the extent of which is often unlimited, 
but split into fissures, that metals are found some- 
times pure, but generally in the state of ores. 
These fissures are commonly encrusted with a white 
shining substance, called quartz by the miners: this 
is generally accompanied with a substance not un- 
like it in appearance, but softer, called spar. These 
two coverings serve as a sheath for tfic vein. The 
more perpendicular the vein, the more is to be ex- 
pected from it. Whenever the miners find a per- 
pendicular vein, they say that it will be very pro- 
ductive. 
« In proportion as the miners descend the fis- 
sures which furnish the metal, the air is always 
warmer ; and the exhalations are sometimes so 
