what are its uses?
Iron accounts for 90% of all refined metals and platinum accounts for 20% of all consumer goods.
Heavy metals
Heavy metals are present in nearly all aspects of modern life. Iron may be the most common as it accounts for 90% of all refined metals. Platinum may be the most ubiquitous given it is said to be found in, or used to produce, 20% of all consumer goods.

Some common uses of heavy metals depend on the general characteristics of metals such as electrical conductivity and reflectivity or the general characteristics of heavy metals such as density, strength, and durability.
what are heavy metals? Metals with relatively high densities and atomic weights. what is its biological role? Period 4 heavy metals are required for certain biological processes.
wiki:18951733
Heavy metals [SEP] Uses
Examples of such atomic properties include: partly filled d- or f- orbitals (in many of the transition, lanthanide, and actinide heavy metals) that enable the formation of coloured compounds; the capacity of most heavy metal ions (such as platinum, cerium or bismuth) to exist in different oxidation states and therefore act as catalysts; poorly overlapping 3d or 4f orbitals (in iron, cobalt, and nickel, or the lanthanide heavy metals from europium through thulium) that give rise to magnetic effects; and high atomic numbers and electron densities that underpin their nuclear science applications. Typical uses of heavy metals can be broadly grouped into the following six categories.