Chemical element or an electrophile; similarly "Nu" denotes a nucleophile. "L" is used to represent a general ligand in inorganic and organometallic chemistry. "M" is also often used in place of a general metal. At least two additional, two-letter generic chemical symbols are also in informal usage, "Ln" for any lanthanide element and "An" for any actinide element. "Rg" was formerly used for any rare gas element, but the group of rare gases has now been renamed noble gases and the symbol "Rg" has now been assigned to the element roentgenium. Isotopes are distinguished by the atomic mass number (total protons and
Zhejiang Huayou Cobalt buying cobalt mined by hand in DRC entirely. Zhejiang Huayou Cobalt Huayou Cobalt Co., Ltd is primarily a supplier of cobalt, including cobalt tetroxide, cobalt oxide, cobalt carbonate, cobalt hydroxide, cobalt oxalate, cobalt sulfate, and cobalt monoxide. It is headquartered in the Tongxiang Economic Development Zone of Zhejiang, China. A subsidiary, Congo DongFang International Mining, has been involved in several controversies around sourcing of cobalt in the Democratic Republic of the Congo. According to a joint Amnesty International and African Resources Watch report, Congo DongFang International Mining, a subsidiary of Huayou Cobalt, sources cobalt from primitive "artisanal" mines in the