174 GEOLOGY OF ASPEN MINING DISTRICT, COLORADO. 
which are almost entirely pure blue limestone. In the ore bodies themselves, 
however, there often occur barren portions which are nearly pure dolomite. 
This shows that dolomization was attendant upon the ore deposition. The 
ore bodies are often separated from the inclosing barren rock by polished 
and striated surfaces, evidently belonging to fractures which were made at 
the same time as the main Silver fault. Along these fractures the limestone 
has often been triturated so as to form the so-called ‘‘talc” of the miners. 
Celeste and Edison No. mines.—'The Celeste and Edison No. 1 shafts start in 
porphyry and run down through shale across the Silver fault into blue 
limestone, and from here down to the Contact fault and the dolomite. Ore 
is found at two main horizons—the Silver fault and the Contact fault. 
The ore in the Silver fault seems to have been rather richer than in the 
lower horizon, while the workings are rather more extensive on the Con- 
tact fault. The ore is identical with that in other mines of the park, 
being a limestone which has been replaced more or less by metallic 
minerals, with a gangue which is chiefly barite. This ore has been nearly 
all oxidized, so that it is soft and crumbling. Its value is very variable, 
ranging from a few ounces in silver to several hundred. There is in the 
lower workings, which run upon the Contact fault, a permanent floor of 
dolomite, which is brown from the oxidation of its iron. Above the ore 
at this horizon is generally blue limestone, which, however, is usually 
altered and may be dolomized. In the drifts may be seen irregular bands 
or tongues of dolomite, which follow the strongly fractured zones and cut 
straight upward across the blue limestone. There is, therefore, evidence 
of two periods of dolomization in this mine, one of which existed before 
the faulting, since it has been faulted regularly in the same manner as the 
blue limestone, and another which was subsequent to the fault, since it 
has been formed in the limestone along fractured zones which accompa- 
nied this faulting. It is significant that the miners call the dolomite where 
it occurs with the ore ‘‘vein lime,” recognizing the fact that it is nearly 
always present in connection with the ore. Through the Edison there 
runs an east-west fault which has a slight downthrow on the north side of 
from 20 to 50 feet and which appears to be the same fault as that running 
through the Good Thunder mine. Along this fault ore has made continu- 
ously in the breccia, the stopes at one point being 60 feet high. 
On the lower level of the Celeste a drift runs a short distance northeast 
