Copper mine is generally composed of sulfide or oxide of copper and other minerals, and reacts with sulfuric acid to produce blue-green copper sulfate. Natural copper minerals come in a variety of colors. Chalcopyrite is bright yellow; bornite is dark copper-red, and becomes bluish-violet speckle after oxidation; chalcogenite (cupric sulfide) is lead gray; copper blue (copper sulfide) is indigo blue; tetrahedrite is steel gray;  the azurite is brilliant blue. In ancient literature, cyan refers to dark blue. The world's proven copper reserves are estimated at more than 600 million tons. The largest is Chile, accounting for about one-third of the world's reserves. Our country has many famous copper mines, such as Jiangxi Dexing, Anhui Tongling, Shanxi Zhong-Tiao Mountains, Gansu Baiyin factory, Yunnan Dongchuan, Heilongjiang Duobaoshan, Jomda County Yulong of Xizang, Maizhokunggar County Qulong and so on. Copper is second only to silver in conductivity in the l kingdom. Copper ore is more abundant and cheaper than silver mine. Now, more than half of the world's copper is used in the power and telecommunications industries.