A coal field estimated to have 7 billion tons of reserve has been discovered in west Canada, making it the largest coking coal field in the world, Canadian Dehua International Mines Group Inc (CDI) said on Thursday. Vincent Li, chief engineer of CDI, told Xinhua that analytic data showed the 150 square kilometers field contains 7 billion tons of coal, most of which is buried within a depth of 1,000 meters, while half of the total reserve is high quality coking coal. The newly discovered mine, located in the Wapiti river area in northeast British Columbia of Canada, surpasses the previous largest field, the Tavan Tolgoi in Mongolia, which has 1.8 billion tons of coking coal in its 6.5 billion tons of coal reserve. The data came from months of studies conducted by Golder Associates, an environment and energy consulting company, the Snowden Consulting Company and China's Shandong Geological Exploration and Research Institute, Li said. CDI was established in 2004 in Vancouver with business mainly in the exploration and mining of coal, iron ore and other minerals.