164

At least some of the galena on No. 3 and No. 4 levels was coarser grained
than that at higher levels. The newly discovered ore below No. 6 level,
however, is reported to be moderately fine grained.

The walls of the ore zone are silicified, sericitized, and impregnated
with pyrite to distances of 10 feet or more from the ore-bodies. Burton
reports the presence of adularia in the rocks immediately adjacent to the
ore.

Some of the ore from near the surface contained many ounces of gold
a ton, one of the early shipments ran 7 ounces to the ton. The quantity
of gold gradually decreased with depth until at No. 4 level the average
was somewhat less than $ ounce a ton. At greater depths the ore averaged
less than 0-4 ounce a ton. Near the surface some ore ran many hundreds
of ounces of silver a ton, and one of the early shipments held 220 ounces a
ton. The quantity of silver decreased with depth at a greater rate than

Ore bodies
Tate
Peas Feldspar porphyry

Bureau of Economic Geolog

Figure 16. Plan of No. 3 level (elevation 1,550 feet), Premier
mine (A-B, C-D, ete.: lines of section, See Figure 17).

that of the gold. On No. 4 level the silver averaged 4 ounces or less, and
at greater depth less than 2 ounces a ton. An indication of the change in
the ratio of gold to silver in the ore is given by the average assay values
of the ore produced each month. In stopes 1A, 1B, and 1C above No. 1
level the ratio of gold to silver was between as 1 is to 40 and as 1 is to 60.
In the same stopes just above No. 2 level the ratio dropped to between as
1 is to 80 and as 1 is to 55. Below No. 2 level the ratio changed gradually
until on No. 3 level it was between as 1 is to 12 and as 1 is to 25. On
No. 4 level the ratio was between as 1 is to 10 and as 1 is to 14. At No. 5
level the stopes converged to form one stope and the ratio changed grad-
ually until at No. 5 level it was approximately as 1 is to 5. Another set
of stopes continuing from No. 1 level down to a single stope on No. &
level showed a gradual change in the gold-silver ratio from about as 1 is