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
Minor metals Indium (In), Lithium (Li), Magnesium (Mg), Manganese (Mn), Mercury (Hg), Molybdenum (Mo), Neodymium (Nd), Niobium (Nb), Iridium (Ir), Osmium (Os), Praseodymium (Pr), Rhenium (Re), Rhodium (Rh), Ruthenium (Ru), Samarium (Sm), Selenium (Se), Silicon (Si), Tantalum (Ta), Tellurium (Te), Titanium (Ti), Tungsten (W), Vanadium (V), Zirconium (Zr) Minor metals Minor metals is a widely used term in the metal industry that generally refers to metals which are a by-product of smelting a base metal. Minor metals do not have a real exchange, and are not traded on the London Metal Exchange (LME). Two characteristics are regularly associated with minor metals: (1)