Thus, metals that are labeled "precious" are also considered noble metals (note, however, that noble metals are not necessarily precious metals). There are nine known precious metals - gold, platinum, iridium, palladium, osmium, silver, rhodium, ruthenium, and rhenium. With the exception of the latter, all are considered noble metals. There are three placer mining methods used to mine placer gold: Gold Panning: This method, which involves the use of a pan, is the oldest and simplest way to extract gold from a placer deposit. In this method, mined ore is placed in a large pan (made either of plastic or metal) and poured with a liberal amount of water; it is then agitated. 1 ounce coin - With 31.103 g platinum content, 31.119 g in weight, and 32.7 mm in diameter. The coins have no currency value. Their value, rather, is equal to their respective platinum contents. All coins consist of 0.9995 pure platinum. On the coin's obverse is Queen Elizabeth II, along with these texts: "ISLE OF MAN" and "ELIZABETH II". Platinum: Most Widely Traded Of The Platinum Group Metals In the periodic table of the chemical elements, six metallic elements - all transition metals - are clustered together and lie in the d-block (the d-block in the periodic table refers to groups 8, 9, and 10, periods 5 and 6). These six elements are collectively referred to as the platinum group metals. Significant amounts of mineable palladium are also found in two other places: the Lac des les igneous complex in northwestern Ontario, Canada and the Stillwater igneous complex in the state of Montana in the United States. Such is the rarity and preciousness of palladium that many metric tons of ore have to be processed to obtain just a troy ounce of the precious metal. Platinum as an investment commodity: As of January 2010, platinum is valued at around us$1,555 per troy ounce (a couple years earlier, its price is about 48% higher than this - considered its peak price). Compared with silver or gold, platinum tends to trade at a higher per-unit price because it is scarcer and has lower mine output.