CHARACTER OF THE METALLIFEROUS VEINS. 
141 
beyond the limits I have stated, on its line of bearing, more 
than half a mile from the original opening upon the tract, 
and another mine has been worked for twenty years, and the 
prospect for the permanence of ore is greater than could have 
been anticipated. The width of vein increases with the depth, 
and no fact is yet brought to light which indicates its discon¬ 
tinuance. 
Veins of magnetic iron are distributed over limited districts. 
Several veins traverse this district in parallel ridges and they 
may be known to belong to separate and distinct veins by the 
dissimilarity of their ores, or of their gangues. Those which 
are only a few feet asunder possess unlike qualities. In de¬ 
ciding upon the number of veins it is necessary to guard against 
deception,as a fold in the strata or an anticlinal axis may place the 
parts of veins in such relations that they may appear to be 
two veins when there is only one. Fig. 27 illustrates the im- 
* 
Fig. 27. 
portance of being on the guard, b, b, The folded lamina of 
gneiss supporting a lean vein of ore, a, a, and indicated by the 
dotted lines. This instance is a plain one, but others of a 
more obscure character will not mislead the observer, provided 
due caution is exercised in his examination. An arrangement 
of veins approximating to the former occurs at the Cook mine, 
where an anticlinal axis seems to occur, and which might at 
first be regarded as a repetition of two veins, admitting that the 
