Uranium (U)It is a rare element with an average concentration of 2.7 ppm in the Earth's crust.In nature, uranium mainly exists in the form of U-238 (>99%), while U-235 (fissile) accounts for only about 0.7%. U-234 contains less than 0.1%Natural uraniumThe size of uranium atoms is relatively large, making it difficult for early crystalline minerals to enter magma. Therefore, it is usually concentrated in the final products of magma crystallization in silicon rich rocks (such as granite) (especially in minerals found in granite, such as zircon, aragonite, and apatite). In such rocks, the uranium content may reach tens or even hundreds of ppm, forming a type of uranium called uraninite or pitchblende (UO)₂）The minerals.

The uranium mining methods include open-pit mining, underground mining, in-situ leaching, and drilling mining (using high-pressure water jets)Low gradeuranium oreUsually contains 0.01% to 0.25% uranium oxide (usually reported as U)₃O₈）； However, some mineral deposits have high uranium concentrations (up to a few percent). In nature, uranium exists in several types of mineral deposits, including unconformity type deposits, Olympic dam type deposits, sandstone deposits, quartz pebble conglomerate deposits, surface deposits (calcareous conglomerate deposits), vein type deposits, volcanic and caldera related deposits, intrusive deposits, and metasomatic rock deposits.

Thorium (Th) is another fissile natural radioactive chemical element.Thorium is three to four times more abundant in the Earth's crust than uranium (9.6 ppm), mainly extracted from monazite sand (a byproduct of rare earth metal extraction).

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