ORE DEPOSITION. 231 
thickness of blue limestone to the overlying shale, being highly mineral- 
ized, so as toform good ore throughout their whole extent. The Contact 
fault, away from the immediate vicinity of these fracture zones, also shows 
evidence of great mineralization, but the ore is generally low grade and 
can not be profitably worked. 
EXTENT OF ORE DEPOSITION. 
The surface extent of the district which has been actually largely pro- 
ductive of ore is practically identical with that of the faulted and uplifted 
region which is centralized in Tourtelotte Park and Aspen Mountain. With 
the disappearance of the faults and the appearance of comparatively 
unbroken strata the ore disappears, as might be expected from the fact 
which has just been pointed out, that ore invariably occurs along these 
faults. in the Hunter Park district, where there has been no faulting, there 
-is also no mineralization, while in the Lenado district, where there are indi- 
cations of a considerable amount of ore, the sections show a local uplift, 
apparently corresponding in nature with that of Tourtelotte Park. The 
main mineralization, however, is restricted to a small surface area, whose 
center is approximately in Aspen Mountain and Tourtelotte Park, and 
on whose borders are Smuggler Mountain on the one side and the 
deposits along the Castle Creek fault in Queens Gulch and southward on 
the other. 
Within this uplifted and broken area ore has formed with an unknown 
vertical extent. he already existing mine workings have a great range in 
point of elevation, extending from the top of Tourtelotte Park down to the 
lowest levels of the Mollie Gibson and Smuggler, which extend nearly 
1,000 feet below the bottom of the Roaring Fork Valley. This gives a 
vertical range of about 3,500 feet, and between these two points the ore is 
practically continuous. At the highest point the ore is found up to the 
grass roots, and at the bottom of the lowest workings there is still the same 
amount of mineralization. The table of analyses given on page 226 
shows that in all this great range there is no important or persistent change 
in the composition or value of the ore, which indicates that it must extend 
downward tor an indefinite but comparatively long distance, and that the 
original ore deposits extended far above the present surface, where they are 
