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,