Wisconsin and Missouri Lead Region. 



37 



Beneath the diff limestone is a thin stratum of bkie Kmestone, 

 and this rests on a body of brown sandstone. As one goes from 

 the southern townships of Wisconsin towards the north, this bkie 

 limestone is observed to become higher and higher in the hills, 

 and the lead diggings to be every where above it. Though the 

 sandstone rocks come out in bold bluff's on the sides of the hills, 

 no veins of ore are ever found in them ; but in the cliff lime- 

 stone above, they are found, though the rock and its fissures lie 

 hid under a great depth of soil. The section annexed (Fig. 1) 

 represents this order of superposition, the character of the fissures, 

 and about the relative proportion that the three rocks bear in the 

 hills near Mineral Point. 



Fig. 1. 



Cliff limestone. 



Blue limestone. 



Sandstone. 



These fissures are of every degree of width, from fifty feet 

 down to thin cracks ; all of them do not contain ore ; the large 

 chambers, when they have any mineral in them, are lined on the 

 walls with a coating of lead ore, seldom over a foot thick, while 

 the interior is filled with clay. Sometimes across the crevices 

 run horizontal layers of galena ; and again it occurs in loose 

 "chunks" in the clay of the fissures or of the soil above, and 

 again it runs in a vertical sheet down, or still again filling narrow 

 fissures in the appearance of a vein and of a bed in the solid rock. 

 But the lead is not the only ore these fissures contain ; mixed 

 with it in every proportion, and even sometimes getting the bet- 

 ter of the galena and shutting it out completely, occur both the 

 carbonate and snlphuret of zinc ; the one known to the miners 

 by the name of "dry bone," the other " black Jack." From the 

 abundance of the carbonate of zinc, and its being an ore that 

 when clear yields about 60 per cent, of the oxide, it seems prob- 

 able that it will sometime become an object of importance ; now 

 it is considered a great obstruction whenever met with, and the 

 galena when mixed with much of the zinc ore, brings an infe- 

 rior price. 



The direction of the fissures downwards is as variable as their 

 size and shape. They run like cracks through a rock — some- 

 times vertically, sometimes inclined, and sometimes horizontally 



