oil is thus regarded by some experts as
the residue of the material which has migrated from the Miocene beds
that probably at one time covered the Nummulitic formations, but have
since been removed by the erosive action of the atmosphere.

~Alum~ is manufactured from the pyritous shales of the Mianwali district,
the annual output being generally about 200 to 300 tons. Similar shales
containing pyrites are known to occur in other parts of this area, and
possibly the industry might be considerably extended, as the annual
requirements of India, judged by the import returns, exceed ten times
the native production of alum.

~Borax~ is produced in Ladakh and larger quantities are imported across
the frontier from Tibet. In the early summer one frequently meets herds
of sheep being driven southwards across the Himalayan passes, each sheep
carrying a couple of small saddle-bags laden with borax or salt, which
is bartered in the Panjab bazars for Indian and foreign stores for the
winter requirements of the snow-blocked valleys beyond the frontier.

~Sapphires.~--The sapphires of Zanskar have been worked at intervals since
the discovery of the deposit in 1881, and some of the finest stones in
the gem market have been obtained from this locality, where work is,
however, difficult on account of the great altitude and the difficulty
of access from the plains.

~Limestone.~--Large deposits of Nummulitic limestone are found in the
older Tertiary formations of North-West India. It yields a pure lime and
is used in large quantities for building purposes. The constant
association of these limestones with shale beds, and their frequent
association with coal, naturally suggest their employment for the
manufacture of cement; and special concessions have recently been given
by the Panjab Government with a view of encouraging the development of
the industry. The nodular impure limestone, known generally by the name
of _kankar_, contains sufficient clay to give it hydraulic characters
when burnt, and much cement is thus manufactured. The varying
composition of _kankar_ naturally results in a product of irregular
character, and consequently cement so made can replace Portland cement
only for certain purposes.

~Slate~ is quarried in various places for purely local use. In the Kangra
valley material of very high quality is obtained and consequently
secures a wide distribution, limited, however, by competition with
cheaply made tiles.

~Gy