Cupronickel invention is the outstanding achievements in ancient China metallurgy technology, in ancient China called the cupronickel "Wu". "The old tang dynasty book youfu zhi" said: "from the rest of a piece of white copper decorated chariot." That is to say, in the tang dynasty, it was stipulated that only the cattle pulled by courtiers could be used as ornaments, indicating that copper was very valuable in the tang dynasty. The copper in question is nickel copper rather than arsenic, because it is resistant to corrosion and is suitable for decorating cattle cars, and because of its unstable nature, it will gradually turn yellow over time due to the volatilization of arsenic.

In ancient Chinese literature, the white copper alloy is called as white copper. This includes three kinds of copper alloys: one is a copper tin alloy with high tin content, such as the "great xia zhenxing" copper money (419 ~ 424 years) and five baht of sui dynasty, which are all tested as high tin bronze without nickel. Another example is a collection of Chinese white bronze mirrors from the nara era (7 ~ 8 centuries) collected by Japan's zhengcangyuan. The other is the copper arsenic alloy containing more than 10% arsenic, namely arsenic white copper; The third is the copper-nickel alloy namely nickel white copper. Among the three types of copper, nickel copper is the most important, followed by arsenic copper.

Yunnan people invented and produced copper, not only in China, in the world is also the earliest, which is recognized by domestic and foreign academic circles.

In ancient times, yunnan produced the most famous white copper, known as "cloud white copper."

By the fourth century a. d., yunnan had a large amount of copper mining and production. In yunnan province, there are still copolymers of copper and nickel, which provide raw materials for the smelting of copper. According to the book of han, "gandhara was a silver rising from the hills of juti in the southwest of the county", and there was a saying that "two silver units of zhuti were first class (two silver units ordered by wang mang at the time)". But according to modern investigation, zhu ti shan (now southwest of yibin, sichuan province) produces copper, nickel and not silver, so "zhu ti silver" may be nickel white copper.

It is generally accepted that China (and the world) has the earliest recorded history of copper in China. "Mantis county, due to the name of the mountains, out of silver, lead, copper, miscellaneous drugs," it said. Mantis county is located in today's yunnan qiaojia old shop town. This area is rich in copper, and the neighboring sichuan province will produce nickel ore, two places linked, from the resources of mantis county can be identified as nickel copper. This is the earliest reliable record of nickel and copper.

These historical records show that China's yunnan province produced copper very early, but at that time it was directly refined from ore containing copper and nickel. Although China has a long history of smelting copper, there is no pure nickel. Yunnan produces arsenite, now known as "arsenicite" in mineralogy. In 1929, king Jin used to analyze the chemical composition of the ancient copper stationery in China; It was shown to contain 6.14% nickel, 62.5% copper and a small amount of tin, zinc, iron, lead, etc.