Cerium in coal is typically weakly negative, meaning that it is present at slightly lower concentrations than the other rare-earth elements. Cerium anomalies in coal are influenced by the sediment source region. Coal mined from mafic regions dominated by basalts, such as the location of the Xinde Mine in China, does not have a Ce-anomaly. In contrast, coal mined in felsic rock regions, such as Guxu Coalfield in China, does have weakly negative Ce-anomalies. Negative Ce-anomalies can also be attributed to the weathering and oxidation of the coal-mining region. During oxidation, Ce precipitates out as CeO, leaving less Ce in the coal.