GeoReM is a Max Planck Institute database for reference materials of geological and environmental interest, such as rock powders, synthetic and natural glasses as well as mineral, isotopic, biological, river water and seawater reference materials. GeoReM contains published analytical data and compilation values (major and trace element concentrations and mass fractions, radiogenic and stable isotope ratios). GeoReM contains all important metadata about the analytical values such as uncertainty, analytical method and laboratory. Sample information and references are also included. GeoReM complements the three earthchem databases: GEOROC, NAVDAT and PETDB.