be a
resumption of mining in the once very productive Huancavelica District
of Peru and in Asia Minor, and with restoration of political order there
may be an increase in output from Mexico and Russia,--but these
districts will be subordinate factors in the world situation. On
geologic grounds, new areas of mercury ores may be looked for in regions
of recent volcanic activity, such as the east coast of Asia, some
islands of Oceania, the shores of the Mediterranean, and the Cordilleras
of North and South America,--but no such areas which are likely to be
producers on a large scale are now known.

GEOLOGIC FEATURES

The chief mineral of mercury, from which probably over 95 per cent of
the world's mercury comes, is the brilliant red sulphide, cinnabar.
Minor sources include the black or gray sulphide, metacinnabar, the
native metal, and the white mercurous chloride, calomel. The ores are
commonly associated with more or less iron sulphide, and frequently with
the sulphides of antimony and arsenic, in a gangue consisting largely of
quartz and carbonates (of calcium, magnesium, and iron). The precious
metals and the sulphides of the base metals are rare.

Mercury deposits are in general related to igneous rocks, and have
associations which indicate a particular type of igneous activity. They
are not found in magmatic segregations, in pegmatites, nor in veins
which have been formed at great depths and under very high temperatures.
On the contrary, the occurrence of many deposits in recent flows which
have not been eroded, their general shallow depth (large numbers
extending down only a few hundred feet), and the association of some
deposits with active hot springs now carrying mercury in solution,
suggest an origin through the work of ascending hot waters near the
surface. The mercury minerals are believed to have been carried in
alkaline sulphide solutions. Precipitation from such solutions may be
effected by oxidation, by dilution, by cooling, or by the presence of
organic matter. Being near the surface, it is a natural assumption that
the waters doing the work were not intensely hot. At Sulphur Bank
Springs, in the California quicksilver belt, deposition of cinnabar by
moderately hot waters is actually taking place at present; also these
waters are bleaching the rock in a manner often observed about mercury
deposits.

The Coast Ranges of California contain a great number of mercury
deposits extending over a belt abo