This is the first comprehensive account of Li-Fe-Mn phosphates (triphylite-lithiophilite and the topotactic alteration products ferrisicklerite-sicklerite and heterosite-purpurite) from 46 granitic pegmatites of the Damara Sequence (Namibia). The Li-Fe-Mn phosphates display a wide range of Fe/(Fe+Mn) ratios. Preliminary ratios 0.125 ≤ Fe/(Fe+Mn) ≤ 0.845 have been determined by wet chemical and microprobe analyses. Relationships appear to be developed between the Fe/(Fe+Mn) ratios and the observed economic minerals, e.g. beryl, Ta-Nb oxides, petalite, and gem tourmaline. There is evidence for regional distribution patterns of Fe/(Fe+Mn) ratios regarding 8 portions and swarms of 4 pegmatite belts. There is fairly good accordance between the degree of fractionation, and differentiation, and the Fe/(Fe+Mn) ratio (hypothesis of Ginsburg) for a great number of pegmatites, although conspicuous deviations from that hypothesis were also noted. From the occurrence of arborescent Li-Fe-Mn phosphates, seen in 22 pegmatites, important arguments could be found for both the mode of the pegmatite evolution and for their economic mineralisation. Recent field observations prove that thermal undercooling is predominantly responsible for the arborescent shape of Li-Fe-Mn phosphates in most of the Damaran pegmatites.