The platinum group metals (PGMs) are six transitional metal elements that are chemically, physically, and anatomically similar.
The PGMs are the densest known metal elements. Exceptionally rare, the six metals naturally occur in the same ore bodies. They are highly durable and, due to their high value, often recycled, giving them long life cycles.
These noble metals are close to each other on the periodic table, and are all referred to as transition metals. They can be further divided into sub-groups: the iridium-group platinum group elements (IPGEs) and the palladium-group platinum group elements (PPGEs).
The six PGMs are: Iridium (Ir), Osmium (Os), Palladium (Pd), Platinum (Pt), Rhodium (Rh) and Ruthenium (Ru).