and-studded Gaspar Strait separates Banka from Billiton. Banka is 138 m.
in length; its extreme breadth is 62 m., and its area, including a few
small adjacent islands, 4460 sq. m. The soil is generally dry and stony,
and the greater part of the surface is covered with forests, in which the
logwood tree especially abounds. The hills, of which Maras in the north is
the highest (2760 ft.), are covered with vegetation to their summits.
Geologically, Banka resembles the Malay Peninsula, its formations being
mainly granite, Silurian and Devonian slate, frequently covered with
sandstone, laterite (red ironstone clay) of small fertility, and alluvium.
The granite extends from W.N.W. to S.S.E., forming the short, irregular
hill-chains. As these lie generally near the east coast, it follows that
the rivers of the west coast are the longer. There are no volcanoes. The
chief rivers (Jering, Kotta and Waringin) are navigable for some 19 m. from
their mouths and are used for the transport of tin. Banka is principally
noted for the production of this mineral, which was discovered here in 1710
and is a government monopoly. It occurs in lodes and as stream-tin, and is
worked by Chinese in large numbers who inhabit villages of their own. The
island is divided into nine mining districts, including about 120 mines,
under government control, with 12,000 workmen, which have produced as much
as 12,000 tons of tin in a year. From May to August, the period of the
south-east monsoon, the climate of Banka is dry and hot; but the mean
annual rainfall reaches 120 in. annually, rain occurring on an average on
168 days each year. The wet, cool season proper is from November to
February, accompanying the north-west monsoon. The heavy rainfall is of
great importance to the tin-streaming industry. The total population of the
island (1905) is 115,189, including 40,000 Chinese and 70,000 natives.
These last are mainly composed of immigrant Malayan peoples. The aborigines
are represented by a few rude hill-tribes, who resemble in physique the
Battas of Sumatra. Rice, pepper, gambier, coffee and palms are cultivated,
and fishing and the collection of forest produce are further industries,
but none of these is of importance. The chief town is Muntok at the north
end of Banka Strait.

See H. Zondervan, _Banka en Zijne bewoners_ (Amsterdam, 1895), with
bibliography; T. Posewitz, _Die Zinn-inseln im Indischen Ocean_. For
geology and the tin-mines, _Jaarboek vor h