Chalk rock is an organic
It is a kind of limestone,
which consists of fossils of tiny calcite
cells of small marine animals.
Other minerals that
are usually present
are clay minerals, apatite, glauconite and silica.
Nodules of other
rocks such as flint and chert can also be present.
Chalk cliffs in southern England. By Pietro Izzo via
It is fine grained
and very soft and easy
It is white or grey in colour.
is used as a fertilizer, in cement, and as a pigment in paints, paper,
rubber, cosmetics, ceramics and other materials.
cliffs on Rugen Island in Baltic Sea. By Frank M. Rafik via
It is not used in the
blacboard chalk, which is manufactured instead.
Much of it was
formed during the Cretaceous
period. Some famous, and excellent deposits
are the White cliffs of Dover in southern England.