The first one on this list is tungsten, with an atomic number 74 and an atomic mass of nearly 184 amu. Tungsten is the second naturally occurring hardest material. And it also has the second-highest melting point among all-natural materials. Notably, the only other material that surpasses tungsten is diamond.
Due to its high melting and boiling points, this rare metal is popularly used in electrical and thermal applications. For example, tungsten wire is mostly used in creating the inner lining of high-temperature furnaces. Apart from this, the metal also finds applications in everyday products such as manufacturing filaments for bulbs.
With an atomic number 42 and a relative atomic mass of 96 amu, this transition metal is also used to add electrical conductivity to alloys. Some common products that contain Mo include engine parts, missiles, drills, saw blades, and so on.
Atomic number 75 and relative atomic mass 186 makes Rhenium one of the rarest metals on earth. And notably, Rhenium is only second to tungsten when it comes to its melting point.
It finds its applications mostly as an additive to molybdenum and tungsten-based alloys. Besides, it is also popularly used as a catalyst in the hydrogenation of fine chemicals. It is also used in filaments for ovens and x-ray machines.
Titanium is one of the most widely used rare metals amongst all. Due to its low bio-activity, it is preferably used as an implant for skeletal injuries. More to it, the metal is also low in density and still offers very high strength.
Its atomic number is 22 and its relative atomic mass is 48. Commercially available titanium has very high tensile strength, which is also one of the reasons for its application as an implant for skeletal fractures. Apart from medical applications, it is also used in aerospace and marine constructions. Though it is 60% denser than aluminum it still offers twice its strength.
Despite their rare occurrence, these transition metals are highly popular for exceptional applications. Most of the transition metals offer unmatched catalytic properties. However, this does not mean that they are not used anywhere else. And the information shared in this article is quite evident of the same.
It is noteworthy that none of the aforementioned metals are radio-active. Meaning, they do not pose a lot of environmental issues, despite being rarely available in the crust. More and more studies are still being carried out to find more uses for these metals.