Heavy metals only mercury, lead and bismuth meet all of them. Despite this lack of agreement, the term (plural or singular) is widely used in science. A density of more than 5 g/cm is sometimes quoted as a commonly used criterion and is used in the body of this article. The earliest known metals—common metals such as iron, copper, and tin, and precious metals such as silver, gold, and platinum—are heavy metals. From 1809 onwards, light metals, such as magnesium, aluminium, and titanium, were discovered, as well as less well-known heavy metals including gallium, thallium, and hafnium. Some heavy metals are either
Hunan Nonferrous Metals Hunan Nonferrous Metals Hunan Nonferrous Metals Holding Group Co., Ltd. is a nonferrous metals company of China. It is a subsidiary of China Minmetals, which in turn indirectly under supervision of State-owned Assets Supervision and Administration Commission. Some of the assets of the conglomerate was listed in Hong Kong Stock Exchange from 2006 to 2015 as "Hunan Nonferrous Metals Corporation Limited" (SEHK: 2626). (The holding company retained Hunan Yaogangxian Mining Co., Ltd., Hunan Huangshaping Mining Branch and a joint venture (Duddar mine).) However, in 2014 China Minmetals announced the plan to privatization of the listed company, which China Minmetals already