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> Every terrestrial concentration process relies on things an asteroid lacks: gravity-driven sedimentation, water-based flotation, density separation in fluids, atmospheric combustion.

That's a good point. Most bulk industrial processes won't work in zero G. This limits asteroid mining. Breaking off pieces of rock and accelerating them to somewhere, maybe. Building a big wheel and spinning it up to get some gravity, maybe. Materials processing in open space, not so much.

The "seed" to start up an industrial economy might be the size of the industrial base of, say, Israel or North Korea, both of which try to be self-sufficient. We get to find out when someone tries to do something self-sustaining on Luna or Mars.

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"Israel or North Korea, both of which try to be self-sufficient" - Neither of them do any such thing though. From a quick search Israel imports about 80% of their calories though they also export some food they are heavily reliant on imported grains and meat. North Korea is obviously harder to get information on but it imports large amounts of food from China.
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Both North Korea and Israel are notable (compared to space) for their dense oxygen rich atmospheres, accessible large reservoirs of water, access to solvents/lubricants, and a generally "shirt sleeves" environment for workers. Asteroids, the Moon, and deep space don't really have these things. So you're not just bootstrapping an industrial facility at those locations but all the basic infrastructure that industry requires to exist.

With space manufacturing the first widget out of a factory costs trillions of dollars. There's also few if any raw materials that are far more abundant in space than here on Earth (at orders of magnitude smaller cost).

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