These two factors may cause the values of gold, silver, and the other precious metals to diminish. Also, the "precious" qualification of a metal is determined by the market value or high demand. Bullion is traded on commodity markets in two forms: bulk ingots or coins, the latter minted by the government of a country. Wollaston's discovery of rhodium was made possible with the use of crude platinum ore. He first dissolved the ore in nitro-hydrochloric acid (also called aqua regia) and neutralized the acid with lye (or sodium hydroxide). By adding salmiac (ammonium chloride), he then precipitated the platinum. All other metals, including rhodium, were precipitated with zinc. mol-1 Electron Configuration: [Xe] 4f14 5d10 6s1 Physical: Density (near room temperature): 19.30 g.cm-3 Liquid Density (at melting point): 17.31 g.cm-3 Melting Point: 1064.18 C, 1947.52 F, 1337.33 K Boiling Point: 2856 C, 5173 F, 3129 K Heat of Fusion: 12.55 kJ.mol-1 Heat of Vaporization: 324 kJ.mol-1 Atomic: Oxidation States: -1, 1, 2, 3, 4, 5 Electronegativity: 2.54 (Pauling scale) Atomic Radius: 144 picometre Covalent Radius: 136 6 picometre Van der Waals Radius: 166 picometre Ionization Energies: 890.1 kJ. dollars per troy ounce in early 2001, when the automobile industry placed a high demand for the precious metal for use as catalytic converters. As an investment commodity, palladium may be bought in forms of bullion coins or bars. Palladium bullion coins are internationally recognized forms of currency and have the ISO codes XPD and 964. Ruthenium: Most Versatile Of The Platinum Group Metals Arranged by name alphabetically, ruthenium is the last of six metallic elements in the platinum group. This precious metal is characterized as being both polyvalent and versatile. In fact, it is known to be more versatile than any of the other five precious metals in the platinum group. The coins in circulation in the United States prior to 1933 were made of 90% gold and 10% copper-silver combined. Canada's official gold bullion coin - The Canadian Gold Maple Leaf - is made of 99.999% gold; and so are these four other gold bullion coins: 1. British Britannia (with a face value of 100 pounds).