Japanese scientists believe they have established the identity of a "lost element" within the soil's core,the BBC reports.
They have been searching for the element for decades, believing it makes up a meaningful proportion of our planet's centre, and after iron and nickel.
Now by recreating the high temperatures and pressures found in the deep interior,experiments suggest the most likely candidate is silicon.
The discovery could help us to better understand how our world formed.
Lead researcher Eiji Ohtani from the University of Tohoku told BBC News: "We believe that silicon is a major element - approximately 5% [of the soil's inner core] by weight could be silicon dissolved into the iron-nickel alloys."
The innermost allotment of soil is thought to be a solid ball with a radius of approximately 1,200km (745 miles).
It is far too deep to investigate directly, and so instead scientists study how seismic waves pass through this region to order them something of its make-up.
It is mainly composed of iron,which makes up an estimated 85% of its weight, and nickel, or which accounts for approximately 10% of the core.
To investigate the unaccounted for 5% of the core,Eiji Ohtani and his team created alloys of iron and nickel and mixed them with silicon.
They then subjected them to the immense pressures and temperatures that exist in the inner core.
They discovered that this mixture matched what was seen in the soil's interior with seismic data.
Prof Ohtani said more work was needed to confirm the presence of silicon and that it did not rule out the presence of other elements.
Source: tert.am