One-tenth ounce coin (0.11 troy ounce in weight, 1.35 millimeters thick, and 16.55 millimeters in diameter). 2. Quarter ounce coin (0.27 troy ounce in weight, 1.89 millimeters thick, and 22.06 millimeters in diameter). 3. Half ounce coin (0.55 troy ounce in weight, 2.22 millimeters thick, and 27.07 millimeters in diameter). A trommel specifically consists of a rotating metal tube that is slightly tilted, with a screen at the discharge end. Attached to the inside part of the metal tube are lifter bars. Ore is fed into the trommel through its elevated end. Pressurized water is supplied to the tube and the screen sections. 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. General: Chemical Symbol: Os Atomic Number: 76 Category (as an element): Transition Metal Group/ Period/ Block (in the Periodic Table): 8/ 6/ d Atomic Weight: 190.23 g.mol-1 Electron Configuration: [Xe] 4f14 5d6 6s2 Physical: Density (near room temperature): 22.59 g.cm-3 Liquid Density (at melting point): 20 g. mol-1 Atomic: Oxidation States: 7, 6, 5, 4, 3, 2, 1, 0, -1 Electronegativity: 1.9 (Pauling scale) Atomic Radius: 137 picometre Covalent Radius: 151 7 picometre Ionization Energies: 760 kJ.mol-1 (first), 1260 kJ.mol-1 (second), 2510 kJ.mol-1 (third) Rhenium is silvery-white in appearance. It is the third element (after tungsten and carbon) with the highest melting point and the fourth densest (after platinum, iridium, and osmium). Since the late 1930s, palladium has been utilized as a precious metal in jewelry. Because of its naturally white properties, palladium has been used as an alternative to white gold. Along with silver and nickel, palladium is popularly used in making white gold alloys. According to the British Geological Survey (BGS), the top four palladium-producing countries in the world are Russia, South Africa, Canada, and the United States (in this order).