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

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Elements<br />

Lead<br />

Oxide minerals<br />

P.8<br />

TABLE P.1.5. Detrital Minerals(a)<br />

Hematite, Fe 20 3 ; Uraninite, U0 2; Uranothorite, (U,Th)) 2 ; Leucoxene, Ti oxide-hydroxide<br />

Sulfide minerals<br />

Cinnabar, HgS; Pyrite, FeS 2 ; Marcasite, FeS 2 ; Chalcopyrite, CuFeS 2; Arsenopyrite,<br />

FeAsS 2 ; Pyrrhotite, FelxS; Molybdenite, MoS 2 ; Cobaltite, CoAsS 2 ; Dyscrasite, Ag 3Sb;<br />

Michenerite<br />

PdBiTe; Geversite, PtSb 2 ; Glaucodot, CoAsS; Moncheite, PtTe<br />

Sulfate minerals<br />

Barite, BaSO 4<br />

Phosphate minerals<br />

Apatite, Ca 5 (PO 4) 3F<br />

Silicate minerals<br />

Actinolite, Ca 2 (Fe,Mg) 5Si 80 2 2 (OH) 2 ; Andalusite, Al 2 Si05; Biotite, K(Fe,Mg) 3A1Si 3O 10 (OH) 2;<br />

Chlorite, (Mg,Fe) 6 (A1,Si) 40 10 (OH) 8 ; Chloritoid, (Fe,Mg) A1 4Si20 10 ; Hornblende,<br />

Ca 2 (Fe,Mg,A1) 5A1 2Si60 2 2 (OH) 2 ; Hypersthene, (Mg,Fe)Sio 3 : Kyanite, A12Si05; Olivine,<br />

(Mg,Fe) 2Si04; Allanite, Ce 2A12FeSi30 1 1 (OH); Sillimanite, A12Si05; Staurolite,<br />

Fe 2AlgSi40 2 3OH; Titanite, CaTiSiO5; Tourmaline, Na(Mg,Fe) 3 A1 6 (B0 3 )3Si 60 1 8 (OH) 4 ;<br />

Zoisite, Ca 3A1 2Si30 110(OH); Gadolinite, Be 2Y 2FeSi 2FeSi 20 10<br />

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

solution substitutions.<br />

Mineral Associations<br />

In addition to defining regions <strong>of</strong> stability for specific mineral phases, geologic evi-<br />

dence indicates which phases may occur together in an equilibrium assemblage. These mineral<br />

associations are good indicators <strong>of</strong> compatible phases. The pegmatite environment contains<br />

many <strong>of</strong> the minerals <strong>of</strong> interest. Rare earth phosphates, rare earth oxides and rare earth<br />

carbonates which are good hosts for the lanthanides and actinides, coexist with a variety<br />

<strong>of</strong> complex silicates, which may host other critical elements. These in-turn coexist with<br />

some <strong>of</strong> the common silicates, which may be more appropriate hosts for 9 0 Sr and 1 37 Cs.<br />

P.1.2 Kinetic Factors<br />

Often the concentration <strong>of</strong> an element in solution is not determined by thermodynamic<br />

solubility data but by the kinetics <strong>of</strong> water-rock interactions. Data on this part <strong>of</strong> the<br />

stability criteria are most urgently needed. We outline here the principal factors that<br />

indicate the kinetic stability <strong>of</strong> various minerals.

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