[en] The determination of lanthanides play an important role in geology as their distribution pattern is widely used for the petrogenetic studies. These elements are present at trace level; therefore the accurate determination of these elements is a difficult task. The ICP-AES is a commonly used instrumental technique for the determination of lanthanides at trace levels, due to its good sensitivity. However, ICP-AES suffers from spectral interference from the major and minor matrix elements in geological materials. Therefore, a selective separation of the trace level lanthanides from the matrix elements is needed. This paper reports a selective homogeneous oxalate precipitation of trace level lanthanides using calcium as carrier