Appendix—geological survey. 
49 1 
back of a lode,” as a Cornish miner would call it, that is extended down into 
the lower formations, the plan to sink a shaft will be in the centre of this 
deposit, as indicated on the surface. The shaft should be sunk to the undis¬ 
turbed rock, and, if the vein is not found there, a drift should be extended 
each way, that is, north and south, from the shaft, on the undisturbed rock. 
In this way, it is certain to find the vein if it is there; and that too, with the 
expense of sinking one shaft, and running two drifts. The cost of sinking a 
shaft and extendtng drifts in this material, with good miners, ought not to 
be much, if anything, over $1.00 per foot. The more I think of those large 
masses of porous, cellular, drusy, jaspery quartz, that lie scattered over the 
surface, and mingled in this heterogeneous mass with other vein like material, 
and good specimens of hematite ore, the more importance I am disposed to at¬ 
tach to this place. It reminds one very much of the upper decomposed portion 
of an extensive mineral vein, or lode, to use a mining term. Such material 
is very often tound over, or very near the most important veins, and some¬ 
times extending down to the depth of a great many feet. It is not the 
result of decomposition only, but the transformation of partially decomposed 
material into faliat is ealled by the Cornish miners, “gossan,” and by the 
German miners, “ iron hat.” It is regarded by the miners of experience 
everywhere, as an important indication, and in many cases is a sure guide, 
to productive veins. The chorus of the German miners’ song is, 
“ There is no lode like that 
Which has an iron hat.” 
Cotta, in describing this, the upper portion of mineral veins in Germany 
in his admirable work on “ Ore Deposits,” says: “ This formation of the iron 
hat in lodes, by the decomposition of the sulphides and spathic iron (fre¬ 
quently extending to a depth of many fathoms), naturally presupposes that 
the sulphides and spathic iron were originally present, and, as these are fre¬ 
quently combined with silver and lead ores or gold, it may be an indication 
of rich deposits of ore.” 
r 
It does not follow, necessarily, because we find mixed with this por¬ 
ous, cellular quartz these oxides of iron, that iron ore only will be found in 
the vein below. They evidently form an essential part of this material we 
call gossan, or iron hat, even where iron ore is not found to prevail in the 
vein below. In this change that has taken place in the upper portion of the 
vein, the original ores are often entirely dissolved and removed, except the 
iron wdiich may remain or be newly formed from the decomposition of other 
ores or minerals. Hence, if a vein is found beneath this gossany out-crop, 
in the town of Rudolph, it is not impossible that other ores beside iron 
may be found in it. Representative specimens of ore and vein material 
from this place are deposited in our museum of practical geology. 
I think there must be other places similar to this, and perhaps much better 
in this neighborhood and to the west of it, but I have not taken time to trace 
them out. My attention was called by Mr. A. Eaton of Stevens Point, to a 
place directly east of this, on the Wisconsin river, just where the Plover river 
