rax in
Thibet, brought out from the mountains on sheep-back.

The United States supplies of borax are sufficient for all domestic
requirements and probably for export. Small quantities of boric acid are
imported, but no borax in recent years. The domestic production comes
entirely from California, though in the past deposits in Nevada and
Oregon have also been worked.

GEOLOGIC FEATURES

The element boron is present in various complex boro-silicates, such as
datolite and tourmaline, the latter of which is used as a precious stone
(pp. 290, 293). None of these are commercial sources of borax. The
principal boron minerals are borax or "tincal" (hydrated sodium borate),
colemanite (hydrated calcium borate), ulexite (hydrated calcium-sodium
borate), and boracite (magnesium chloro-borate). Commercially the term
borax is sometimes applied to all these materials. These minerals appear
in nature under rather widely differing modes of origin.

The borax production of Italy is obtained from the famous "soffioni" or
"fumaroles" of Tuscany. These are volcanic exhalations, in which jets of
steam carrying boric acid and various borates, together with ammonium
compounds, emerge from vents in the ground. The boric acid material is
recovered by a process of condensation.

Borates, principally in the form of borax, occur in hot springs and in
lakes of volcanic regions. The Thibet deposits, and those formerly
worked at Borax Lake, California, are of this type. Certain of the
hot-spring waters of the California coast ranges and of Nevada carry
considerable quantities of boron, together with ammoniacal salts, and in
some places they deposit borax along with sulphur and cinnabar. It seems
probable (see p. 40) that these waters may come from an igneous source
not far beneath.

Most of the borax deposits of California, Nevada, and Oregon, though not
at present the largely producing ones, and probably most of the Chilean
and adjacent South American deposits, are formed by the evaporation of
desert lakes. They are products of desiccation, and in Chile are
associated with the great nitrate deposits (pp. 102-104), which are of
similar origin. The salts contained in these deposits are mainly borax,
ulexite, and colemanite. The sources of these materials are perhaps
deposits of the type mentioned in the last paragraph, or, in California,
certain Tertiary borate deposits described below. Whatever their source,
the borates are carried in solu