TOURTELOTTE PARK. 167 
ered. This ore is different from the other ores of the camp, being char- 
acterized by an abundance of coarsely crystalline iron pyrite, inclosed in 
soft black material, which appears to have been triturated. The pyrite was 
analyzed in the laboratory of the Survey and proved to be simply iron sul- 
phide, containing also small amounts of arsenic, lead, copper, and zine, a 
small amount of silver, and traces of cadmium, cobalt, and nickel. Assays 
of this ore were also made to determine whether the values were chiefly in 
the pyrite or in the inclosing black material. The two, being separated as 
well as possible, were separately assayed. The pyrite assayed 14 ounces in 
silver, while the black cement assayed 90 ounces. No gold was found by 
either of these assays. 
Homestake shaft— The Homestake shaft of West Aspen Mountain must be 
distinguished from the Homestake deep shaft farther to the east. The 
former lies on West Aspen Mountain, on the northwest side of the Mary B. 
fault. It is in the basal Maroon gray limestone, and in some of its workings 
the gray and red sandstones of the Maroon are cut. Near the end of the 
drift, to the southeast, a crosscut west encounters the Mary B. fault and 
crosses it into dolomite. The strike of the Mary B. fault at this contact is 
N. 50° E. 
Baltic tunne—T'he Baltic tunnel starts on the east side of West Aspen 
Mountain and runs in a westerly direction to the Pride fault. It is 780 
feet long and passes through 155 feet of glacial drift and other débris, then 
through mingled shale and porphyry to the fault plane at the breast. On 
the west side of the fault is granite. 
TOURTELOTTE PARK. 
There is no actual break between the Tourtelotte Park district and 
that of Aspen Mountain, since ore is found continuously from one to the 
other. Just south of the Durant mine, however, the steep northern face 
of the domelike uplift flattens toward the south, and with it the Aspen 
Mountain syncline becomes shallow. These changes become more marked 
farther south, especially the flattening of the syncline, so that the dip of 
the formations, and with them of the Silver and the Contact faults, along 
which are the chief ore-bearing localities, becomes much slighter than on 
Aspen Mountain. Most of the workings in Tourtelotte Park are, therefore, 
comparatively close to the surface. Ore is found continuously from Aspen 
