Europium anomaly

The europium anomaly refers to the enrichment or depletion of the europium concentration in a mineral or rock compared to neighboring rare-earth elements also present in the material. This anomaly is typically evaluated relative to a common standard such as a chondrite or mid-ocean ridge basalt (MORB). In geochemistry a europium anomaly is said to be "positive" if the Eu concentration in the mineral is enriched relative to the other rare-earth elements (REEs), and is said to be "negative" if Eu is depleted relative to the other REEs.