# The Azimuth Project Thorium (changes)

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Thorium (Th) is a transition element in IVB group of the periodic table with atomic number 90. The natural isotope is thorium 232 with half-life of $1.4 \times 10^10$ years (14 milliards, or 14 US billions) decaying via $\alpha$-decay; other isotopes (228, 230, 231, 234), are found only in traces and 229 only synthesized in the laboratory. Thorium 232 is more abundant (by factor of 4-5) in Earth’s crust than all the isotopes of uranium combined and it does not require isotopic separation; 25% of the world reserves are estimated in India.