242 The American (it'ohxjist. October, 1893 
Hut the beds are not without cavernous spaces or "openings," 
such as arc ordinarily called "vugs." We may make two 
broad or comprehensive divisions or groupings of the deposits 
into 1. Irregular and breceiated deposits; and 2. Regular 
sheets or beds. 
In the irregular and breceiated we may include most of the 
dry-bone derived from the oxidation of the blende in place, 
which dry-bone continues to occupy the same places and 
passes downwards into unchanged blende. Sometimes the 
original bedding of the rocks is but little changed, and there 
is no disturbance, but in other places there is great confusion 
and breaking up of the bedding with the accumulation of ir- 
regular masses of rock, surrounded and invested with a coat- 
ing of ore, by which the rocks are united into one mass. 
Brecciated Deposits. 
In all of the deposits of blende and pyrite, not only in those 
formed in the midst of a breccia but in the regularly formed 
horizontal beds, there are places where the ores have been 
broken across, with the layers disjointed, so as to show fault- 
ing of these layers on a small scale, but such breaks have 
been recemented and reunited as strongly as before. It is 
evident that there has been movement, probably in most cases 
by the falling down of masses of ore by their own weight, 
when perhaps the rocks below became eaten away or the soft 
clays became washed out, thus removing the support. 
In the case of the brecciated deposits, where no distinctly 
regular flat sheets are seen, the original bedding of the rocks 
themselves is obliterated or destroyed by the falling-in. It is 
not always easy to decide whether the broken condition of the 
beds is the cause or the effect of the percolation of mineral 
solutions, but I incline to the view that, in most cases, it is 
the result of the flow of the solutions of acid salts of the 
metals which have eaten away the rocks below without fully 
replacing them in bulk, and that being so undermined the 
rocks have fallen in from time to time, and in the confused 
masses of fragments the zinc and iron sulphates have found 
the most favorable conditions for deposition or replacement. 
The Varieties of Ore. 
There are now four different kinds of ore shipped from the 
Wisconsin mines, namely: 
