pitchblende

There are uraninite (pitchblende) ores that are getting on for 10% uranium, or 0.07% 235U, so a tonne of ore would yield 7 kg of 235U.

Just look for low albedo and alpha particles from pitchblende.

It contained a tremendously rich lode of uranium pitchblende.

I'm not sure we'd need to burn through the resulting refined product of 50 million tons of pitchblende to run the entire planet for 75 years.

It's astonishing to me that people in the early 1900s could measure and calculate the charge on an electron, or that Marie Curie had to process tons of pitchblende to purify micrograms of Radium - and could, and did.

The ore already in the United States contained 65 percent U3O8, while the pitchblende aboveground in the Congo amounted to a thousand tons of 65 percent ore, and the waste piles of ore contained two thousand tons of 20 percent U3O8.

On the other hand, we were handed on a silver platter a huge supply of hand sorted pitchblende from the Belgium Congo, with an average uranium content of 60-65% (!!!), without that we wouldn't have finished in time to finish the war.

Back in the day, a child could pick up chemicals and do experiments at home - one day Sacks' parents told him, "We'll install a fume cupboard for you, but can you make less poison gas next time?" You could also be legally under-age and not allowed to vote yet, but you could just buy pitchblende (uranium) and several other radioactive substances for your experiments.