198 ECONOMIC GEOLOGY OF SILVERTON QUADRANGLE, [bull. 182. 
mill were abandoned, and in 1899 the workings were not accessible. 
The mill is equipped with roasting furnace, crusher, two sets of rolls, 
trommels, three sets of mixing troughs, and vats. The ore was appar- 
ently treated by the Angnstin or a similar process. 
Silver Link mine. — This mine is situated on the east side of the 
canyon, about a mile north of the Micky Breen lode. Its principal 
adit is a crosscut tunnel 1,700 feet in length. The course of the lode 
is about N. 12° W. It is nearly vertical. This tunnel was run in the 
early eighties. According to the Mint reports, the total product of 
the mine for the years 1888, 1890, and 1891 was nearly $50,000. The 
mine had been idle since 1873, but was reopened in 1899. 
The tunnel mouth is in Algonkian quartzite and schist, but the cross- 
cut soon passes into the overlying San Juan breccia. The latter lies 
upon a clean and very uneven erosion surface, showing local varia- 
tions in relief to the extent of 100 feet or more. Sometimes a breccia 
of schist and quartzite fragments mingled with andesitic material 
rests directly upon the Algonkian and grades upward, without break, 
into the typical andesitic San Juan breccia. There is no trace of 
movement or mineralization along this contact plane. 
The lode is a sheeted zone, 20 feet or more in width. The ore is 
chiefty bornite and tetrahedrite, carrying silver and chalcop}^rite, and 
occurs as bunches along some one of the fissures. It is found in 
quartz, which is largely silicified San Juan breccia. It contains from 
20 to 30 per cent of copper and sometimes as much as 300 ounces of 
silver per ton. The best ore is said to occur in solid quartz. There 
has been considerable post-mineral movement along the lode, result- 
ing in soft gouge, and where the disturbance is pronounced it is 
regarded as unfavorable for ore. The ore usualty occurs near the 
west (called the foot) wall, but it is far from continuous. The coun- 
try rock on both sides of the lode is traversed by numerous parallel 
fissures, along which there has frequentty been some late movement, 
as attested by the presence of wet clay gouges. 
An old shaft was sunk on the lode for 60 feet below the tunnel 
level, but apparently did not reach the bottom of the andesitic breccia. 
Thus it is impossible to gain from this occurrence any light on the 
important question of what changes, if any, take place in an ore- 
bearing lode as it passes from the Tertiary breccia to the Algonkian 
schist. In 1900 this old shaft was being reopened, and it is possible 
it may be carried down into the schists. 
The country rock in the vicinity of the Silver Link mine is inter- 
sected by numerous fissures, with a general trend of a few degrees 
west of north, and therefore approximately parallel with the Silver 
Link vein. Many of these fissures can be seen extending southward 
across the Uncompahgre to Mount Abrams. Their average strike, as 
seen on the surface, appeared to be about N. 5° W. Their dip is 80° 
to 85° to the east. At the mine these fissures, which do not, as a rule, 
