Isotope Ratios
The relative amounts of different forms of the same element in a sample, used to trace geological history and chemical processes.
The proportions of different isotopes of an element present in a material or sample. Isotopes are atoms of the same element with different numbers of neutrons, making them slightly heavier or lighter. Scientists measure these ratios to understand geological age, temperature history, chemical reactions, and the origin of rocks and minerals.
What this means in real life
A geologist analyzes oxygen isotope ratios in ancient zircon crystals to determine whether they formed in hot or cool conditions billions of years ago—different ratios reveal the temperature of the environment when the crystal grew.
What it isn’t
Not a measure of radioactivity or decay rate. Isotope ratios describe the natural abundance of stable or unstable forms side-by-side; they are not the same as half-life or how fast an isotope breaks down.
Commonly misused online
Often conflated with 'carbon dating' or radioactive decay. While radioactive isotope ratios can date objects, most isotope ratio work in geology uses stable isotopes that never decay, serving as chemical fingerprints instead.