My periodic table poster is now available! Spark plug. This spark plug claims that unlike ordinary spark plugs that have a platinum alloy electrode, it has a pure platinum center electrode. It also claims to use yttrium in the ground electrodes. Source: Auto Parts Store Contributor: Theodore Gray Acquired: 10 January, 2003 Text Updated: 11 August, 2007 Price: $5 Size: 3" Purity: >90% Sample Group: Spark Plugs