Richly endowed with mineral resources, the province ranks high in reserves of copper , lead, zinc, gold and silver. Other significant mineral and metal deposits include aluminium, tungsten, molybdenum, crude oil, coal, wood, soda, quartz, marble and mica. The province's deposits of gold and graphite are among the largest in China. It has the richest oil reserves in China, and Daqing Oilfield is the earliest and largest oil field in China supplying a third of the country's crude oil. The province 's coal reserves amount to around 10 billion tons. It leads the country in timber reserves with a total of 1.8 billion cubic metres. It produces 90 per cent of the national annual production of flax. It is a major centre for the cultivation of sugar beet. Major crops in the province are soya beans, maize, wheat, sorghum, sugar beet and cured tobacco . Its milk production is the highest in China.