Consider the question. The Earth's crust is made of approximately 5 % of heavy metals by weight, with iron comprising 95 % of this quantity. Light metals (~ 20 %) and nonmetals (~ 75 %) make up the other 95 % of the crust. Despite their overall scarcity, heavy metals can become concentrated in economically extractable quantities as a result of mountain building, erosion, or other geological processes.

Which heavy metal has highest concentration in earth's crust?
If the answer is 'iron'; explain the reasoning:
To answer the question, consider the following: The Earth's crust is made of approximately 5 % of heavy metals by weight, with iron comprising 95 % of this quantity.