•244 ECONOMIC GEOLOGY OF SILVERTON QUADRANGLE, [bull. 182. 
quartzite" appears to be the same as the massive quartzite here 
included in the Algonkian. His "pink quartzite" is evidently the 
silicified telluride conglomerate, while his "lower quartzite" could 
not be identified in the Saratoga workings. He states that it is pene- 
trated by the Jackson tunnel, about 800 feet southwest of the Sara- 
toga, but this tunnel is no longer accessible. A truer representation 
of the ore body and its relations to the inclosing rocks is believed to be 
afforded by the rough diagram, fig. 2->. 
In 1900 a drift was being run along the ore-bearing horizon toward 
the northeast with the object of ascertaining whether any ore has 
been deposited at the intersection of this horizon by the large vein 
cut in the tunnel above. This seems an advisable piece of prospect- 
ing. Hitherto the development has been rather unsystematic, and it 
was not discovered until 1900 that the large oxidized ore bodies were 
continuous, with sulphide ores passing beneath the andesitic breccias 
to the eastward. 
Baltic group. — This group, comprising the Maud S., Mono, and 
other claims, is a prospect in Brooklyn Gulch, south of the Saratoga. 
The principal work at present is in connection with the Mono lode, 
which strikes N. 43° E. and dips northeast at about 75°, and is reached 
by a tunnel through the limestone about 400 feet in length. This 
lode occupies a fault fissure of at least 100 feet throw, which drops 
the overlying andesitic breccia on the southeast until it lies against 
the limestone. The ore, consisting of nearly solid pyrite and chal- 
copyrite, occurs as a vein in the fault fissure and as a relatively flat 
replacement deposit between the limestone and overlying andesite on 
the northwest side of the fault. Where both walls of the fissure 
are andesitic the vein is narrow; but where one wall is limestone it 
widens, evidently b} T replacement of the calcareous wall. There has 
been some post-mineral movement along the fault fissure, as shown 
by the presence of gouge and slickensides. 
The ore is low grade, carrying at-its best about 30 ounces of silver 
and 12 per cent of copper. Ore of this general character is very 
abundant both here and in the Saratoga mine, but can not at present 
be economical^ worked. 
It is evident that the ore bodies have been only partly prospected. 
No attempt has been made to find the ore which very likely exists at 
the top of the limestone on the down thrown side of the fault. This 
would seem to be an excellent opportunity to employ a diamond drill, 
provided the known ore bodies indicate that the ore on the other side 
of the fissure is worth searching for. 
The Maud S. is also on a fault fissure, which crosses the gulch near 
the mouth of the Mono tunnel. Its general strike is N. 30°-40° E., 
and its dip southeast at about 85°. This also is a normal fault, let- 
ting down the andesite against the limestone on the southeast for at 
least 25 feet. Some argentiferous copper ore was formerly taken 
