Concordia diagram

A Concordia diagram is a chart used by geochronologists to determine the age of mineral samples, especially zircon crystals. It plots two isotopic ratios (usually ^<207>Pb/^<235>U and ^<206>Pb/^<238>U) against each other. When a mineral is originally formed or later disturbed, its data points move along a curve called the Concordia. If the points lie on the curve, the age is reliable. If they are below, it indicates that some lead has been lost or gained, helping scientists understand the sample’s history and accurately date geological events.