But while platinum is generally resistant to corrosion, it is corroded by certain elements, such as cyanides (potassium cyanide or sodium cyanide), caustic alkalis, sulfur, and any of the five halogens (astatine, bromine, chlorine, fluorine, and iodine). The following lists some of the properties of platinum: General: * Chemical Symbol: Pt * Atomic Number: 78 * Category (as an element): Transition Metal * Group/ Period/ Block (in the Periodic Table): 10/ 6/ d * Atomic Weight: 195.084 g. Its principal application is in the making of certain parts of jet engines. Here, the metal is added to high-temperature nickel-based superalloys. Other uses of rhenium are as follows: 1. As catalysts in making lead-free, high-octane gasoline. 2. As filaments in making ion gauges, mass spectrographs, and photoflash lamps. Apart from being traditional coinage metals (along with copper), both gold and silver are also well known for their uses in jewelry and art; they likewise have certain industrial uses. A third important factor that will qualify an element as a precious metal, as may be noted from the uses of gold and silver above, is that it should not be radioactive. Their respective "largest" titles, however, carry further qualifications. The Welcome Stranger Gold Nugget: The exact distinction given of this gold nugget is: "the largest alluvial gold nugget ever found". It was discovered on February 5, 1869 at Moliagul, a small township in Victoria, Australia about 37 miles west of the city of Bendigo. Ruthenium - VIIIb/5; Ru -> Ru2+ + 2 e-; 0.455 V 2. Rhodium - VIIIb/5; Rh -> Rh2+ + 2 e-; 0.600 V 3. Palladium - VIIIb/5; Pd -> Pd2+ + 2 e-; 0.987 V 4. Silver - Ib/5; Ag -> Ag+ + e-; 0.7996 V 5. Osmium - VIIIb/6; Os + 4 H2O -> OsO4 + 8 H+ + 8 e-; 0.838 V 6. Iridium - VIIIb/6; Ir -> Ir3+ + 3 e-; 1.156 V 7. This composition was meant to make the coins more durable and harder and thus resist dents and scratches, as, again, they were originally intended for circulation. On the obverse of the Krugerrand is the face of Stephanus Jonannes Paulus Kruger, fifth president of the South African Republic (note the surname Kruger and the South African currency Rand were combined to give this precious metal coin its name).