Exploration for rare earth element (REE)-deposits hosted in carbonatites and associated rocks is challenging because of the heterogeneous distribution of REE and the variable and often complex mineralogy of such REE mineralisation. The Keishöhe in southwestern Namibia is a subvolcanic intrusion consisting of calcite-carbonatite, dolomite-carbonatite, ankerite-carbonatite dykes, ring dykes and diatremes, and is regarded to be a part of the Kudu lineament carbonatite complexes. Importantly, it exemplifies many of the problems associated with REE exploration – particularly regarding its heterogeneous REE distribution. It is therefore an excellent site in which to explore the processes related to REE precipitation in detail. Petrography, whole rock geochemistry and microXRF imaging of xenolith-bearing and xenolith-free carbonatites provide insight into the role of silicate xenoliths in the development of a hydrothermal or supergene REE mineralisation in a subvolcanic environment. Xenolith-rich carbonatites are almost barren, whereas xenolith-free carbonatites show REE-contents of up to 10 wt. % total REE (TREE). Therefore, the probability for REE-enrichment in the various Keishöhe carbonatites is significantly higher in the absence of silicate rock xenoliths. The REE mineralisation is dominated by REE-F-carbonates, while monazite is a minor constituent. In contrast to other complexes, where Si assimilation caused REE depletion in the melt during the magmatic stage, this study demonstrates post-magmatic hydrothermal or supergene REE mobilisation and enrichment. REE remobilisation and enrichment is caused by hydrothermal or supergene alteration of silicate xenoliths (Si release) by aqueous fluid(s). In combination with previous studies this study clearly shows that silicate xenoliths have 1) a significant influence on REE-mineralisation in general and 2) may act either positively (precipitation/incorporation) or negatively (mobilisation) on the mineralisation of discrete REE phases depending upon the related syn-magmatic or post-magmatic processes. Key Words : Carbonatite, Ring dykes, Rare Earth Elements, MicroXRF, Sperrgebiet, Tsau-‖Khaeb- (Sperrgebiet)-National Park, southern Namib, Mineralisation, Xenoliths.