Abundance of elements in Earth's crust
The abundance of elements in Earth's crust is shown in tabulated form with the estimated crustal abundance for each chemical element shown as mg/kg, or parts per million (ppm) by mass (10,000 ppm = 1%). Estimates of elemental abundance are difficult because (a) the composition of the upper and lower crust are quite different, and (b) the composition of the continental crust can vary drastically by locality.