Radioactive heavy minerals are found in beach sands of northwest Palawan as dark bands, laminations and streaks in an otherwise white silica sand. The heavy minerals were derived from granitic intrusives underlying Mt. Capoas, Erawan Point and Bay Peak. These occur as minor accessory minerals in the granite. Monazite, rutile anatase, allanite, zircon and sphene were identified in the detritus. Speciments of granite studied show only zircon and allanite. The radioactive elements associated with the heavy minerals are uranium and thorium. In addition high concentrations of rare earth minerals were found in a number of samples.

Uranium occur in greater amounts in monazite; lesser in sphene and zircon and much less in allanite. Uranium as U₃O₈ ranges from 0.0037% to 0.76%, Thorium content is greatest in monazite and allanite, less in sphene and zircon. Thorium as ThO₂ ranges from 0.17% to 9.65% Rare earths ranges from 3.3% to 64.85%.

Test by the International Atomic Energy Agency in Vienna Austria indicate that the U₃O₈ contained in the heavy minerals are not recoverable by current leaching methods. For the present, the U₃O₈ can be viewed as by-product of the extraction for thorium.