Geochemistry is the study of the chemical makeup of Earth and other planets. Geochemists investigate what rocks, minerals, soil, and water are made of at the chemical level, tracking how different elements move through Earth over time.

When a geochemist examines a rock sample, they might discover it contains iron, silicon, oxygen, and other elements in specific proportions. By analyzing these chemical fingerprints, they can figure out how old the rock is, where it formed, and what conditions existed when it formed. Geochemists study everything from how metals concentrate in certain areas (which helps miners find valuable deposits) to how carbon moves between the atmosphere, oceans, and rocks (which helps us understand climate change).

While a regular chemist might study reactions in a laboratory, a geochemist applies chemistry to understand our planet's history and processes. They might analyze volcanic gases to predict eruptions, study ocean chemistry to understand coral reefs, or examine moon rocks to learn how our solar system formed. Geochemistry helps answer fundamental questions about where Earth's water came from, how the atmosphere developed, and even how life began.