Editing Thorium and Thorium Reactors — Master Overview (section)

=== Primary Reference Data ===

{| class="wikitable"
|-
! Property !! Value
|-
| Element name || Thorium
|-
| Chemical symbol || Th
|-
| Atomic number || 90
|-
| Atomic mass || 232.038 u (Th-232, the only naturally occurring isotope; trace Th-228, Th-230, Th-234)
|-
| Classification || Actinide; radioactive metal
|-
| Natural state || Solid metal; silvery-white when freshly cut; darkens to grey on exposure to air
|-
| Discovered || 1828 by Swedish chemist Jöns Jacob Berzelius; named after Thor, Norse god of thunder
|-
| Radioactive type || Alpha emitter; weakly radioactive; less radioactive than uranium
|-
| Half-life (Th-232) || 14.05 billion years — approximately three times the age of the Earth
|-
| Abundance in Earth's crust || Approximately 6–10 parts per million (ppm); average cited as 10.5 ppm; three to four times more abundant than uranium
|-
| Primary ore minerals || Monazite (a phosphate mineral); thorianite; thorite
|-
| Primary mining byproduct || Thorium is found in association with rare earth elements (REEs) and is frequently a byproduct of rare earth and titanium mining
|-
| Fissile? || No — thorium-232 itself is not fissile; it is fertile
|-
| Fertile? || Yes — Th-232 absorbs a neutron to become Pa-233 (protactinium-233), which decays to U-233 (fissile) in approximately 27 days
|-
| Fissile product || Uranium-233 (U-233); one of only three fissile isotopes in the universe
|-
| Energy density (theoretical) || 1 tonne of thorium can produce as much energy as 200 tonnes of uranium or 3.5 million tonnes of coal in a breeder configuration
|-
| Weapons use (historical) || Thorium dioxide (ThO2) used as a refractory material; historically used in gas mantles; limited weapons application (U-233 from thorium is one pathway to weapons material, though complicated by U-232 contamination)
|-
| Dominant reactor type for thorium || Liquid Fluoride Thorium Reactor (LFTR); Molten Salt Reactor (MSR)
|-
| World's largest reserves || India (~25% of world reserves in monazite sands); Brazil; Australia; United States; Turkey; India's large reserves are a primary driver of its ambitious national thorium energy program
|}