Mainly conflict metals: Tungsten, tin, tantalum and gold are referred to as 3TG or 3Ts and gold.

Tantalum is used primarily for the production of capacitors, particularly for applications requiring high performance, a small compact format and high reliability, ranging widely from hearing aids and pacemakers, to airbags, GPS, ignition systems and anti-lock braking systems in automobiles, through to laptop computers, mobile phones, video game consoles, video cameras and digital cameras. In its carbide form, tantalum possesses significant hardness and wear resistance properties. As a result, it is used in jet engine/turbine blades, drill bits, end mills and other tools. (From Wilkipedia)

Tin is also commonly a component of biocides, fungicides and as tetrabutyl tin/tetraoctyl tin, an intermediate in polyvinyl chloride (PVC) and high performance paint manufacturing. (From Wilkipedia)

Tungsten is a metal of many superlatives. It has not only the highest melting point of all elements expect carbon (3422℃) but also excellent high temperature mechanical properties and the lowest expansion coefficient of all metals. A temperature of about 5700℃ is needed to bring tungsten to boil- which corresponds approximately to the temperature of the sun's surface. With its density of 19.25g/cm3, tungsten is also among the heaviest metals. Its electrical conductivity at 0℃ is about 28% of that of silver which itself has the highest conductivity of all metals.

Gold is used in jewelry, electronics, and dental products. It is also present in some chemical compounds used in certain semiconductor manufacturing processes. (From Wilkipedia)