Density of U235, specifically… you could crystallize pure uranium in the Earth’s crust today, and it would not be enriched enough for a nuclear reactor.

So in the continental crust the abundance of uranium is more than one hundred times greater than the average abundance of uranium in the entire Earth or in the Solar System.

Otherwise uranium would have been almost the least abundant chemical element, as it is on average in the entire Solar System.

Tin is among the metals that are depleted in the crust of the Earth. Elsewhere tin is a few hundred times more abundant than uranium.

A continental crust like on Earth can appear only on planets that have been melted, so that the light and heavy minerals have combined and separated by density, with the continental crust floating over the molten magma and then solidifying. Most of the Earth has been melted by the collision that has formed the Moon, but possibly also by other smaller collisions.

In most other places in the Solar System it will be unlikely to find so easily accessible and abundant uranium as here on Earth.