THE PRECIOUS METALS

The eight precious metals are: silver, gold, platinum, palladium, rhodium, ruthenium, iridium, and osmium.

The world's annual production of precious metals, valued at more than a billion dollars, is approximately 6500 tons of silver, 1000 tons of gold and only 20 tons of the six platinum metals combined. More than half of the production of platinum metals is platinum. The rest is mostly palladium. Rhodium, ruthenium, iridium and osmium are very scarce.

For production of jewelry, made of the so· called "solid" metals, the pure precious metals are hardened and strengthened by alloying. Silver and gold are alloyed with base metals, copper being the common hardener. Platinum and palladium are alloyed with the precious metals iridium and ruthenium, and the resulting alloys contain little, if any, base metals.

SILVER

Pure silver, an element, is a white, soft, ductile metal melting at 1761 OF. A cubic inch of silver weighs 0.379 lb. avoir. or 111 dwt.