Only ~13% of the world's phosphate is mined in Morocco today, so it's a rather different situation.

And of course, phosphate reserves are only a small portion (0.02%) of the world's estimated phosphate resources.

Yeah, China quit exporting them a couple of years ago.

Moreover, they are famously the limiting element in Isaac Asimov's thought-experiment of converting the earth's crust into biomass.

Ooh, I would like to learn/see links about that!

I think it's sort of a companion bit to the short story 2430 A.D. The story line is a bit different but the internet suggests that as an addendum or companion article he did a kind of back of the envelope calculation going from the elemental composition of the earth's crust to maximum biomass. Basically, you'd run out of phosphorus first. Much of the crust would still remain because silicon and aluminum are mostly unused and although iron is used, there's still far too much of it after you run out of phosphorus.

https://en.wikipedia.org/wiki/2430_A.D.