W. H. YON STREERtJWITZ-GENESIS OF CERTAIN ORE VEINS. 
67 
It would take too much time to investigate here what forces had 
caused the tremendous fissures, and all the possible and probable chemi¬ 
cal, physical, and mechanical processes which were active in changing 
and rechanging the original combinations into others; therefore I con¬ 
fined myself to showing how these cavities in the quartz may have been 
formed and filled with nearly any kind of ore or mineral. 
For the formation of the quartz gangue from an alkaline hydrous 
then gelatinized magma argues also the fact that the white color of the 
quartz, its opacity, is caused by microscopic cavities containing mostly 
carbonic acid, which is easily retained in a viscous gelatinized material, 
but not in a crystalline or amorphous precipitation to which Von Ruhs- 
hofen, Becker and others refer. 
Becker mentions in his monograph on the Comstock lode the prevailing 
existence of the ore along the hanging wall, and the presence of clayey 
deposits there. Both these phenomena can be reproduced in vessels. 
Alumina salts, like the salts of other metals, grow up in veins, only 
some of them quicker and more massy than others, which supports the 
conclusion that clayey deposits could be formed along the hanging wall 
before the veins of other metals were grown up; or we may also accept 
the possibility that the aluminous veins absorbed gradually the other 
metals, just as they did in my experiments. 
Not to tax too severely your patience, I shall mention only a few more 
cases in which this particular mode of ascension can be applied, and these 
cases briefly. . 
At the Hazel mine, in Trans-Pecos Texas, the fissure is rent in a red 
sandstone, which is underlaid by granites, porpt^ritic rocks, and diabase. 
The rock surrounding the fissure holds no silver or copper, which are the 
ores of this mine. We have also here to abstract from the lateral secre¬ 
tion idea. 
Considering also here the quantity of ore and the character of the vein 
in this mine, it is absurd to suppose that a fissure of an average width of 
35 feet and of a traceable length of more than two miles, together with 
other parallel veins, was filled from ore deposits above like the one di¬ 
rectly under the carboniferous limestone, which limestone holds no sil¬ 
ver and no copper. 
It is rather probable that this deposit was formed by a vein or veins 
grown up in fissures through the sandstone, terminating on its surface, 
and forming there the horizontal deposit. 
A similar deposit here directly on crystalline igneous rock, I found 
in Mexico. 
In Mies, Bohemia, the ore-bearing quartz gangues run up between 
barren clay slates, and are filled in a similar way by ascension. 
