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Figure 7. Idealized schematic of 238U, 218Po, 214Po, and 210Po halos.

Figure 8. 238U halo in fluorite. (× 535)

Figure 9. 218Po halo in fluorite. (× 535)

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Figure 10. 214Po halos in mica. (× 250)

Figure 11. 218Po halos in mica. (× 250)

Figure 12. The Spectacle Halo, an overlapping series of 210Po halos discovered in a piece of biotite from the Silver Crater mine, Faraday Township, Ontario. Reproduced from ref. (3) by permission of Nature. (× 560)