Geologic Distribution: Thorium is an important component in the mineral monazite, (Ce, La, Y, Th)PO4, also zircon and xenotime1,2. Monazite was found in trace amounts in 22 of 24 coal samples examined using scanning electron microscopy (SEM) in an unpublished study by the WVGES and probably is present in most coals. Thorium may also be associated with iron oxides and clays 3. Thorium correlated moderately well with ash yield, ash related elements as well as several rare earth element components of monazite. Coals from the upper Kanawha Formation through the Conemaugh Group in southern and northeastern West Virginia contained the highest thorium contents. Coals of the lower Kanawha Formation and below contained less thorium, and the Upper Pennsylvanian Pittsburgh, Redstone and Sewickley coals were very low in whole coal thorium.
Economic Impact: Thorium in West Virginia coals has no direct economic impact. Thorium is used in the preparation of the Welsbach mantle used for portable gas lights 4. Thorium is also an alloying cement in magnesium, as a coating on tungsten wire in electronic equipment, used in high refractive index lenses, and used as a catalyst in the petroleum and other industries 4.
Environmental Impact: Environmental concerns of thorium in coal is primarily with its radioactivity 3.
1. Palmer, C.A. and Filby, R.H., (1984)
2. Finkelman, R.B., (1981)
3. Swaine, D.J., (1990)
4. CRC Handbook of Chemistry and Physics
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Page last revised: November 9, 2005