Although the Imperial vein is a fissure of great length and depth, all
the material that is included between the porphyritic walls is not pay
ore. The ore occurs in shoots of greater or less extent, the same as in
any other vein. The gangue is chiefly quartz, having a pearly luster
resembling in appearance some light grayish lead carbonate at a casual
glance. Accompanying the quartz, though in minor quantities, are baryta,
calcite, and black manganese oxide. The value of the ore lies almost
wholly in its silver contents, which occur as chloride and sulphide
(argentite) accompanying pyrites, chalcopyrite, and iron oxides. The
silver sometimes occurs with copper glance in small bunches in solid
masses of lead carbonate. Such ores are very high grade. In one of the
branches gold is found with only a small percentage of silver, the
reverse condition, however, usually obtains. The silver frequently is
found in the same shoots with the base ores and in quartz without any
intimate association with either lead, copper, or iron. The galena is
sometimes very low grade, carrying only 4 ounces per ton in silver. In
one shoot the lead carbonate contains over 200 ounces. It is a notable
fact that no good ore is found in quantity without copper in some form,
either as sulphide (glance) or carbonate. Chloride of silver is also
found associated with iron and manganese, without copper or lead.