236 GEOLOGY OF ASPEN MINING DISTRICT, COLORADO. 
element is rare in sedimentary beds. It is often found in the feldspars, 
and forms an essential constituent in one variety—hyalophane. Sand- 
berger’ has shown that most of the metals found in veins as sulphides are 
present in eruptive rocks, probably as original constituents, especially in 
the dark-colored silicates, such as biotite, hornblende, and olivine. The 
heated waters would then be propelled upward, as is actually the case in 
all hot springs, and, finding their readiest channels along the faults which 
traverse the uplifted area, would follow them and deposit their contents 
where conditions were favorable. 
CHANGES IN ORE SINCE DEPOSITION. 
MECHANICAL CHANGES. 
Since the deposition of the ore many of the faults have continued 
moving and some new ones have come into existence. In this way ore 
which has been formed in place along a fault has often been broken, and 
even triturated, by subsequent movement along the same plane. This phe- 
nomenon is continually shown along the Silver fault in Smuggler Mountain 
and many other mineral-bearing faults Where new faults have developed 
since the ore deposition the ore bodies have often been displaced and their 
parts more or less widely separated. The displacement by the Clark fault 
in the Smuggler and Mollie Gibson mines is an example of this. Along 
such faults the ore occurs in the breccia, having been dragged up from the 
solid mass. The ore at Lenado is supposed to be a larger example of this 
same process, the broken-up condition showing that it has been subjected 
to great movement since its deposition 
CHEMICAL CHANGES. 
Formation of native silver _—Native silver is of very common occurrence in the 
ores immediately below the oxidized zone. In the rich polybasite ore of 
the Mollie Gibson and Smuggler it often forms a very important constitu- 
ent. This native silver is generally associated with the carbonaceous Weber 
shale. It is sometimes solid and massive, but very often spun into wires 
1¥. Sandberger, Untersuchungen itiber Erzgiinge, 1882. 
