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Management of Commercially Generated Radioactive Waste - U.S. ...

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Element minerals<br />

P.7<br />

TABLE P.1.4 Placer Minerals(a)<br />

Platnium, Osmium, Palladium, Iridium, Platiniridium Iridosmine, Osmiridium, Ferropla-<br />

tinum, Gold, Electrum, Silver, Diamond<br />

Oxide minerals<br />

Tantalite, FeTa20 6 ; Thoreaulite, ThTi 206; Cassiterite, Sn0 2 ; Samarskite, YNb 20 6 ; Bad-<br />

deleyite, Zr02; Euxenite, YNb 20 6 ; Chromite, FeCr 20 4 ; Magnetite, Fe 3 0 4 ; Columbite,<br />

FeNb 20 6 ; Polycrase, YTi 206; Aeschynite, YTi 206; Loparite, CeTi 206; Ilmenorutile<br />

(Ti,Nb) 30 6 ; Ilmenite, FeTi03; Zirkelite, CaZti 207; Pyrochlore, Ca 2Nb20 6OH; Rutile,<br />

Ti02; Brookite, Ti02; Anatase, Ti02; Corundum, A1203; Spinel, MgAl 20 4 ; Quartz, Si0 2<br />

Tungstate minerals<br />

Phosphates<br />

Carbonates<br />

Silicates<br />

Ferberite, FeWO 4 ; Wolframite, (Fe,Mn)W0 4 ; Hubnerite, MnW04; Scheelite, CaWO 4<br />

Monazite, CeP04; Xenotime, YPO 4<br />

Bastnaesite, CeCO 3F; Parisite, Ce 2Ca(CO 3) 3F 2<br />

Thorite, ThSi04; Zircon, ZrSiO 4 ; Garnet, (Fe,Mg) 3A12Si30 12 ; Topaz, A12SiO 4F 2 ; Phenakite,<br />

Be 2SiO 4<br />

a. Simplified formulae are given. Actual minerals usually contain many additional solid<br />

solution substitutions.<br />

and silicates are known placer minerals and therefore are potential lanthanide and actinide<br />

phases. Some low density minerals, such as quartz, spinel, garnet, corundum and diamond<br />

also occur in placers.<br />

Other minerals might be on this list <strong>of</strong> placer minerals under special conditions. If<br />

the sedimentary conditions are more reducing than usually occurs in nature, uraninite and<br />

many sulfide minerals may survive. This possiblity is evidenced by the placers <strong>of</strong><br />

Witwatersrand District <strong>of</strong> Africa, which formed in the reducing environments <strong>of</strong> the<br />

Pre-Cambrian.<br />

Detrital Minerals<br />

A great many minerals survive long distances <strong>of</strong> transport in stream beds, although the<br />

final fraction <strong>of</strong> that mineral is <strong>of</strong>ten much lower than in the source area. These minerals<br />

are listed in Table P.1.5. The rate <strong>of</strong> degradation <strong>of</strong> some <strong>of</strong> these minerals may be suffi-<br />

ciently slow to allow that phase to be a host for radionuclides. Minerals such as apatite,<br />

barite, allanite and titanite are particularly interesting. Apatite and allanite contain<br />

significant amounts <strong>of</strong> lanthanides and actinides. Strontium varieties <strong>of</strong> apatite also<br />

occur.

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