Lead and zinc are obtained from mines near the towns of Madan and Rudozem, in the eastern Rodopi, and in the western part of the Stara Planina, at Eliseyna and Chiprovtsi. A new lead mine is under development at Erma Reka, in the vicinity of Madan. The Rodopi mines account for the major portion of the ore output. The ore is processed in flotation plants near the sites of the mines and is refined at Kurdzhali, Plovdiv, and Kurilo. Production of refined lead and zinc rose rapidly in the first half of the 1960s but leveled off in the second. Substantial amounts of these metals have been exported, mostly to Western Europe. Exports, however, have been declining both in volume and as a proportion of output. The decline has been more pronounced in the case of lead, and lead exports dropped from 65 percent of output in 1960 to 22 percent in 1970. The volume of lead exports fell from 53,500 tons to 22,100 tons in the 1965-70 period. Zinc exports declined from highs of 78 percent of output in 1965 and 58,100 tons in 1966 to 64 percent of output and 48,100 tons in volume in 1970. Bulgaria also possesses small reserves of gold, silver, and uranium. Gold has been found near the town of Trun, not far from the border of Yugoslavia. Silver and uranium deposits are located in the western Stara Planina. The uranium ore is processed by the Rare Metals Combine near Sofia. Gold and silver are also obtained as by-products in the smelting of copper, lead, and zinc. Information on reserves and production of these metals is not available. Aluminum and tin must be imported. Other Raw Materials There are reported to be adequate resources of nonmetallic minerals for the production of cement and other building materials, glass, and ceramics. Asbestos, salt, sulfur, and cement are produced in quantities large enough to allow some exports. The quality of asbestos, however, is low, and better grades must be imported for some uses. Exports of cement declined from 715,000 tons in 1965 to 153,000 tons in 1970. Timber and wood pulp from domestic sources are in short supply. Under an agreement with the Soviet Union, Bulgaria has supplied 8,000 workers to the timber industry of the Komi Autonomous Soviet Socialist Republic for the development of Siberian timber resources, in return for which the Soviet Union has undertaken to export to Bulgaria about 900,000 cubic yards of timber in 1973 and up to 2 million cubic yards per year after 1975. Similar arrangements exist with regard to paper pulp, iron and steel, natural gas, and other raw materials. Domestic agriculture provides ample raw materials for the food processing industry, but only a fraction of light industry's needs for fibers and hides. In the 1968-70 period average annual imports of these materials included cotton, 60,000 tons; wool, 2,900 tons; synthetic fibers, 26,000 tons; and cattle hides, 7,700 tons. In addition to the raw cotton, cotton textiles in the amount of 63,000 tons were imported annually.