l the mines in the Sacramento and San Joaquin river-basins were idle
till, in 1893, Congress appointed a Debris Commission. These mining
engineers issue licenses to work the mines when satisfied that the
debris will be kept out of the rivers. There are in the state many
hundred thousand acres of gold-bearing gravel lands yet untouched,
that could be worked by hydraulic mining.

In drift-mining the rich gravel is covered by hard lava rock thrown
up by some old volcanic outburst. Tunnels are driven by blasting with
dynamite, or by drilling under the rock to reach the gravel which
usually lies in the buried channel of an old river. The long drifts,
or tunnels, needed are very expensive and only mine owners with
capital can work these claims.

Richest of all are the quartz mines, where beautiful white rock, rich
with sparkling gold, is found in veins, or "lodes," cropping out of
hillsides or dipping down under the earth. The great "Mother-lode"
of our state runs like an underground wall across Amador, Calaveras,
Tuolumne, and Mariposa counties and has been traced for eighty miles.

Some poor miner usually finds a ledge of quartz-rock and digs down the
way the ledge goes. He puts up a windlass, worked by hand, over the
well-like hole he has dug out, and hoists the ore out in buckets. But
he soon finds, as the hole or shaft goes deeper, that he must timber
the sides to keep them from caving in, that he must have an engine to
raise the ore and a mill to crush the hard rock. So he sells out to a
company of men, who put in costly machinery, deepen the shaft, and by
heavy expenditure get large returns.

The quartz ledges dip and turn, so tunnels and cross-cuts are run to
follow the golden vein, and all these are timbered with heavy wooden
supports to keep the earth and rock from falling in on the men. The
miners work in day and night gangs, using dynamite to break up the
hard rock, and sending ore up in great iron buckets, or in cars if the
tunnel ends in daylight, on the hillside. Sometimes the miners
strike water, and that must be pumped out to keep the mine from being
flooded.

The ore is crushed by heavy stamps, or hammers, and then mixed with
water and quicksilver. This curious metal, quicksilver, or mercury,
is fond of gold and hunts out every little bit, the two metals mixing
together and making what is called an amalgam. This is heated in an
iron vessel, and the quicksilver goes off in steam or vapor, leaving
the go