38 Wisconsin and Missouri Lead Region. 



between the strata. Bat in all cases on reaching the sandstone, 

 they are, as far as is yet known, unproductive. They are fol- 

 lowed when they are found to yield three inches of galena, that 

 being the least vein it is thought worth while to pursue through 

 rock ; and it is very rare indeed that a continuous vein is found 

 exceeding one foot in thickness. The horizontal direction of the 

 fissures is more uniform ; those producing the most ore almost 

 universally running nearly east and west. Near Mineral Point, 

 some fissures running north and south produce good ore, but they 

 are for the most part horizontal beds (of limited width) between 

 the strata, and out of these directions it is rare to find a produc- 

 tive fissure. The smelters think they can distinguish the ores 

 that are found in different fissures — that from an east and west 

 fissure being perfectly crystallized, of a smooth surface, strias in- 

 distinct ; that from a north and south fissure, of crystalline struc- 

 ture, with two sets of strise very distinct, crossing each other at 

 right angles ; and the ore from a quartering fissure crystalline, 

 with many sets of striae crossing each other obliquely ; and to 

 some extent I had opportunity of proving their observations cor- 

 rect. The fissures appear to be limited in length to within a 

 few hundred feet, and to lie in ranges which extend at right an- 

 gles with the direction of the fissures. In the neighborhood of 

 Mineral Point many of these fissures are opened and mined, and 

 the "diggings" are seen to extend with little irregularity in a 

 north and south belt, that part to the west producing lead ore ; 

 half a mile to the east the fissures containing copper ore, and still 

 further east a mile or more, hematite iron ore abounds in them. 



The deepest shafts that have been sunk on these fissures are 

 about ninety feet ; and at Mineral Point they may be worked to 

 that depth without the water being troublesome. But as these 

 deep shafts were sunk on the highest ground, the bottom of them 

 hardly reaches the sandstone. 



Copper Ores. — The copper ore is similarly situated to the lead 

 ores, either in wide fissures or in thin veins running through the 

 rock. As many as four of the little veins not exceeding two 

 inches in thickness have been found running about east and west 

 on different parts of the mining ground. The ore in these is a 

 mixture of the sulphuret and carbonate. Besides these, which 

 are not considered important, there is a large fissure, in places 

 fourteen feet wide, that has been traced about a quarter of a mile. 



