The "rare earths" are actually just as common as Si. It just shows we won't be running out of them anytime soon, it's just a matter of finding ways to extract them.
Si is the symbol for silicon, which is the second most abundant element in the Earth's crust (after oxygen.) The REEs are certainly not as abundant as that. Si is 270,000 ppm; cerium is 60 ppm.
Not a million times more rare, more like ~10,000 times. Also, Ni is more abundant in the oceanic crust than the continental crust. Lots of Ni in mantle rocks (peridotite is about 0.1% Ni.)
It's interesting comparing the abundance of copper (and even more so, tin) and iron. It was a huge transition in resource availability when the iron age began.
I’m not sure how you’re interpreting that graph, because Si (Silicon) and Na are orders of magnitude more common than the rare earths. You might have missed that it’s a logarithmic scale.
The "rare earths" are actually just as common as Si. It just shows we won't be running out of them anytime soon, it's just a matter of finding ways to extract them.