INDICATIONS OF VEINS-EXTENT-LEAD AND ZINC. 
181 
INDICATIONS OF THE PRESENCE OF A VEIN BENEATH. 
§ 109. It has been observed that where a sink hole occurs 
there is a probability of finding lead. So, when a series of 
them can be traced upon the surface in an east and west direc¬ 
tion, there is probably a fissure in connection with them, which 
will prove to be lead-bearing. Depressions, miniature ravines, 
the presence of barytes in the debris, or calc spar, become in¬ 
dications of the existence of a vein fissure in the neighborhood. 
In 'prospecting for lead, the miner looks for the above indica¬ 
tions. Mineral gravel, the existence of the Coscinopora Sul¬ 
cata, Goldf., is regarded also by Mr. Owen as indicative of the 
presence of a vein in the vicinity. 
The galena is associated with blende, calamine and sulphu- 
ret of copper. Instances occur when calamine displaces the 
galena and becomes the principal mineral of the lode. 
EXTENT OF THE LEAD-BEARING ROCKS OF THE WEST. 
§ 110. The lead region comprehends eighty townships, or two 
thousand eight hundred and eighty square miles, and is about 
one-third larger than the state of Delaware. The length ot 
the lead region, from east to west, is eighty-seven miles, and 
its greatest width, from north to south, fifty-four miles. The 
produce of the mines of the upper Mississippi, exceeds 50,000,- 
000 of tons annually, which is probably less than one-half the 
quantity this region is capable of producing under increased 
facilities and a better system of mining. 
LEAD AND ZINC OF NEW YORK, MASSACHUSETTS AND 
CONNECTICUT. 
§ 111. The lead mine of South Hampton, Massachusetts, was 
opened as long ago as 1810. Its value has never been deter¬ 
mined. The vein together with the gangue is seven or eight 
feet wide at the surface, is vertical, and is included in granite. 
