HELP on TERRESTRIAL ABUNDANCE ∞g/kg (microgram per kilogram) (plotted on a logarithmic scale)
This is a plot of the overall elemental composition of the Earth, expressed as 'mass fraction in parts per billion, that is ∞g/kg. This is the most 'problematic' of the abundance plots here, containing rather ad hoc adjustments and corrections. Only four elements have an abundance higher than ten percent; being iron, oxygen, silicon and magnesium, together making up more than 90% of the mass. Whereas the crust (comprising just 0.5% of the mass of the Earth) contains mostly oxygen, silicon, and aluminium in the form of aluminium silicate rocks, the mantle (comprising 67% of the mass of the Earth) contains a higher proportion of magnesium. The core (at 32%) contains predominantly iron and nickel, (this we know from analyses of iron meteorites thought to be once the core of some now smashed planet) with some cobalt, and perhaps sulphur.
