Wisconsin and Missouri Lead Region. 61 
to reach a vein that will make a show, and attract a purchaser. 
The fissure is in limestone, its greatest width about four feet, and 
has been traced east and west about fifty yards. 
Mine La Motte.—This tract of country is about twenty miles 
east of the Iron Mountain, and is celebrated as containing some ~ 
of the oldest and most profitable mines in Missouri. It consists 
of 24,010 acres of land, over different parts of which lead ore 
has been raised for more than one hundred years, .The rock 
formation over the most of it is the sandstone and limestone, in 
horizontal strata. ‘Through these, a rock resembling granite has 
forced its way, and forms ridges and ledges, which make up the 
remainder of the tract. It is a hard compact rock, composed of 
quartz and feldspar without mica, and usually of a red color. At 
its point of contact with the limestone are frequently found hori- 
zontal seams of ore, both copper and lead, and these are also 
found in many places where no rock at all is exposed for several 
feet down 
The following section shows the position of one of these cop- 
per ore veins as far as it has yet been followed. 
Ps ao 
A 
“the taaiericdiebeda Philadelphia: mines. Ai 
carbonate, mixed with what I then took for black oxide of cop- 
per, and a considerable proportion of ochre. Until the specimens 
arrive, and I have an opportunity of carefully examining them 
1 cannot speak positively of their richness. What I mistook for 
black oxide of copper in a specimen I preserved from another 
locality in this tract, I have since found to be an oxide of cobalt 
and manganese, as will be seen fartheron. And I now believe 
the black earthy mineral that forms a considerable part of the 
mass of some of the copper ores at the Philadelphia mine, to be 
the same oxide of cobalt and manganese. The ore is found ina 
bed consisting. of clay with layers of slate and ore irregularly 
mixed. It is under a stratum of limestone which is very near 
