PERSISTENCE OF VEINS IN DEPTH. 
131 
the depth of 1500 or 1600 feet; and the quicksilver mines of 
Almaden, in Spain, have sustained their richness beyond the 
depth of 900 feet. 
The continuity of veins in the direction of their strike, has 
not been determined with exactitude. Some of the veins of 
Freyberg are known to extend, in length, from 12,000 to 24,000 
feet. Another is known to extend 36,000. But in the direction 
of their strike or bearing, there is a great variation in their 
condition. An auriferous vein of quartz in Maryland, extend¬ 
ed only 20 or 24 feet in its line of bearing, plunging down at 
each extremity on a rapid slope; and yet there is little doubt 
that its depth continuously is as great as any of the auriferous 
veins of our country, whose line of bearing may be traced for 
one or two miles. The records of mining furnish many curious, 
as well as interesting facts. Veins are often explored for seve¬ 
ral years without returning a compensation for the labor and 
expense incurred, when they are abandoned. After many years 
of rest, an enterprising miner or capitalist, who is acquainted 
with the history of its former working, having faith in its value, 
reopens the mine and pursues it with great success. Occurrences 
of this kind are common in all mining countries. They show in 
the first place what superior skill may accomplish; or, indeed, the 
subsequent success may have arisen not so much from superior 
skill in working, as from having opened a richer part of the 
mine. All experience in mining proves that the wealth of a 
mine is variable; some zones are rich, while others are compara¬ 
tively poor; and this fact is one which should be universally 
known; it is one which the capitalist should be prepared to meet 
in any mine, however rich it may be at certain points of explo¬ 
ration. This remark is applicable to veins of lead, copper, 
silver and gold, rather than of iron. 
Veins have been observed to terminate in the direction of 
their strike, in many thin branches, which appear to be lost in 
the rock. It is not, however, determined that those smaller 
branches are always the extreme ends of those veins, for the 
fissure may have opened wider beyond their apparent termina- 
