red mineral cemented with lac, it occurs
in the Salem district, Madras, in Mysore and in Rewa. Large deposits of
corundum exist in the United States, especially in N. Carolina and
Georgia, where they are associated with peridotites, often near contact
with gneiss. The mineral has been extensively worked, as at Corundum
Hill, Macon county, N.C., near which, in 1871, were discovered numerous
rubies, sapphires and pebbles of coarse corundum in the bed of a river.
Corundum occurs also at many localities in Montana, where the crystals
are often of gem quality. They are found mostly as loose crystals in
gravel, but are known also in igenous rocks like andesite and
lamprophyre. Prof. J. H. Pratt, who has studied the occurrence both in
Montana and in N. Carolina, considers that the alumina was dissolved in
a molten magma, from which it separated at an early period of
consolidation, as illustrated by the experiments of J. Morozewicz.
Corundum occurs also in Canada in an igneous rock, a nepheline-syenite,
associated with Laurentian gneiss. Important deposits were discovered by
the Geological Survey in 1896, in Hastings county, Ontario; and corundum
is now worked there and in Renfrew county. New South Wales, Queensland
and Victoria are other localities for corundum. The mineral is found
also in the Urals and the Ilmen Mountains, in the Alps (in dolomite), in
the basalts of the Rhine, and indeed as a subordinate rock-constituent
corundum seems to enjoy a wide distribution, being found even in the
British Isles.

See Joseph Hyde Pratt, "Corundum and its Occurrence and Distribution
in the United States," _Bulletin U.S. Geol. Surv._, No. 269 (1906); T.
H. Holland, _Economic Geology of India_ (2nd ed.), Part i. (1898).
(F. W. R.*)

CORUNNA, a maritime province in the extreme north-west of Spain; forming
part of Galicia, and bounded on the E. by Lugo, S. by Pontevedra, W. and
N. by the Atlantic Ocean. Pop. (1900) 653,556; area, 3051 sq. m. The
coast of Corunna is exposed to the full force of the Atlantic; it forms
one succession of fantastically shaped promontories, divided by bays and
estuaries which often extend for many miles inland, with reefs and small
islands in their midst. Though well lighted, this coast is very
dangerous to navigation, gales and fogs being frequent in winter and
spring. The most conspicuous headlands are Cape Ortegal and Cape de
Vares, the most northerly points of the Spanish seaboard, and C