How many elements is the earth made of?

Even in trace amounts, the highest atomic number element found in nature is Plutonium, which is found in Uranium deposits from natural fission and some primordial Plutonium in the crust left over from a supernova that added material to the molecular cloud the solar system was formed from. The periodic table goes up to 118, but many of the higher atomic numbers are synthetic, are only made in the lab, and are not found in nature.

The entire earth (not just the crust) is estimated to be primarily composed of iron, oxygen, silicon, magnesium, and nickle by MASS; by NUMBER, oxygen, magnesium, silicon, iron, and aluminum (top 5); take note that elements like oxygen, magnesium, silicon, and iron tend to combine to form ROCK. The accounting above is in NUMBER, even trace amounts of very rare elements are counted.

The entire earth, the Milky Way galaxy, the solar system, the earth's crust, and the universe are all abundant, according to a fantastic article on Wikipedia.

The abundance of chemical elements is a wiki page at https://tutor.hix.ai

The majority of the Earth's crust, mantle, and core are made of these elements: iron, oxygen, silicon, magnesium, sulfur, nickel, calcium, and aluminum.