History Of Precious Metals
The valuable, relatively rare, and highly corrosion resistant metals, which are found in the periodic table in the vertical groups VIIIB and IB and the horizontal periods 5 and 6, are called the precious metals. They include (with atomic numbers) ruthenium (44), rhodium (45), palladium (46), silver (47), osmium (76), iridium (77), platinum (78), and gold (79). The platinum group metals include (along with platinum): ruthenium, rhodium, palladium, osmium, and iridium. The three most popular precious metals are gold, silver, and platinum. They have historically been valued for their beauty and rarity, and are commonly referred to as the precious metals. Platinum usually costs slightly more than gold, and both metals are about 80 times more costly than silver. Precious metal weights are given in Troy ounces (named for Troyes, France, known for its fairs during the Middle Ages) a unit approximately 10% larger than 1 oz (28.35 g).