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
Permanente Metals Permanente Metals Permanente Metals Corporation (PMC) is best known for having managed the Richmond Shipyards in Richmond, California, owned by one of industrialist Henry J. Kaiser's many corporations, and also engaged in related corporate activities. These four of the seven west coast Kaiser Shipyards were known for their construction of Liberty ships. The company was also a major producer of magnesium during World War II. To make use of its major product, powdered magnesium, PMC also developed and supplied an incendiary bomb mixture of magnesium powder, asphalt, gasoline and others components (known as "goop", with similar characteristics to napalm); 17,000