What is "ultra-pure iron" with a purity of up to 99.9992%?

More than 2,500 years ago, pre-Qin craftsmen gazed upon molten copper and tin, writing "Six Elements of Metal" in the *Kaogongji* (Record of Trades), thus forging the solemnity of bronze ritual vessels and the sharpness of weapons. Through changing times, the spirit of craftsmanship remains constant. From the ancient philosophy of "examining the curves and shapes to refine the five materials" to the continuous emergence of new materials such as ultra-pure iron, perovskite, and carbon fiber, China's materials industry is growing rapidly from its millennia-old fertile soil, moving towards a new technological frontier. The first industrial culture program, *The Record of Chinese Trades*, jointly produced by China Media Group and the Ministry of Industry and Information Technology, will launch its new materials episode on CCTV-1 (China's main channel) at 8:00 PM on November 2nd, with an exclusive online premiere on CCTV Video.