Tungsten is known as "industrial tooth" or "industrial salt" because both of its melting point and specific gravity are much higher than other metals, while its hardness is only second to diamond. Currently, China is the world's largest tungsten ore resources owner and producer. In 2013, China’s tungsten ore reserves hit 1.9 million tons, accounting for 54.3% of the world; its tungsten concentrate (WO365%) output was 138,000 tons, equivalent to 84.5% of the global output.