Shuangyashan, city, eastern Heilongjiang sheng (province), far northeastern China. Located some 265 miles (430 km) northeast from Harbin, the provincial capital, Shuangyashan is a new city that has grown up since 1949; its importance is based almost entirely on coal production. The coalfields under the city, on the northern slopes of the Wanda Mountains, have estimated reserves of more than 10 billion tons of high-quality coal. Almost the entire population of the city depends on the coal industry. Most of the coal mined is transported by rail to the steelworks at Anshan in Liaoning province and to other industrial centres in the Northeast China region (Manchuria). A few coal pits opened there during the late 1920s, but the city’s growth began in earnest in the 1950s as the mines were developed; Shuangyashan’s population soon exceeded 100,000. Though it remains essentially a mining city, some power-generating, machinery, metallurgy, chemical, electronic, and timber industries have been developed. In addition to coal deposits, iron ore and gold have been found in the area. Pop. (2002 est.) 436,642.