FWIW, the author certainly knows about Shinkolobwe, which is mentioned in these book scans hosted on the author's site: http://blog.nuclearsecrecy.com/misc/1989-Hewlett-Holl-Atomsf... , http://blog.nuclearsecrecy.com/misc/1962-Hewlett-Anderson-Ne... , and http://blog.nuclearsecrecy.com/misc/1969-Hewlett-Duncan-Atom... .

At http://blog.nuclearsecrecy.com/2013/02/25/the-secret-song/ we can see the author quoting from the first of these.

A look at Hewlett & Holl finds:

> The far-flung complex of mines, ore-processing mills, feed material plants, gaseous-diffusion plants, production reactors, chemical separation plants, metal fabrication plants, and weapon component and assembly plants was still largely concealed behind the security barriers established by the Atomic Energy Act ...

> Of the 3,700 tons of uranium concentrates (U308) that the Commission received in 1953, only about one-quarter (1,100 tons) came from mines in the United States; the rest was produced in the Belgian Congo (1,600 tons), South Africa (500 tons), Canada (400 tons), and Portugal (100 tons). ...

> As for foreign sources, the leveling off of production from the Shinkolobwe mine in the Belgian Congo would be more than offset by projections of rapidly increasing deliveries later in the decade from the Union of South Africa and Canada. ...

Hewlett was (quoting the author) "the first official historian of the Atomic Energy Commission ... [whose] volumes on AEC history are extremely useful resources."