HELP on LITHOSPHERIC ABUNDANCE % (percentage) (plotted on a logarithmic scale)
This is the abundance or the relative amount of an element (expressed as a percentage of the total mass) contained within the lithosphere. The lithosphere is that part of the Earth containing the atmosphere, the oceans and the upper 16km of the crust. Note that oxygen is the most abundant element at 49%, followed by silicon, aluminium and iron at 26%, 8% and 5% respectively. Some are estimates only, being highly dependant on the (improbable) discovery of all known ore deposits. Several, such as radon, are radioactive and exist in equilibrium amounts by the radioactive decay of other elements. Technetium and promethium, for which there exist no stable isotopes, are present in trace amounts only, with actinium being the rarest.
