Only 12 types of metal were known a few hundred years earlier. At present, over 3500 different materials exist just in the steel industry. There also exist more than 340,000 metal grades, described by ...

In the 1870s, Congress authorized nine banks in California to issue National Gold Bank notes which were redeemable in gold coin. These well-worn notes survive as tangible evidence of the rush for gold ...

During the tumultuous late 19th century, the U.S. government found it necessary to increase its reserves of precious metals. The Treasury offered certificates in exchange for deposits of gold and ...