The Dumper Dew is a newly discovered pegmatite located on the eastfacing slope of Uncle Tom Mountain in Oxford County, Maine. It is a geochemically evolved LCT-type pegmatite petrogenetically linked to the middle Paleozoic Sebago batholith. Shallow emplacement of the Dumper Dew is evidenced by abundant miarolitic cavities found in the pegmatite. The sheet-like structure of the pegmatite coupled with its intrusion in lowmetamorphic grade country rock suggests rapid crystallization. Northern portions of the wall zone and intermediate zones have undergone hydrothermal alteration by the migration of late-stage fluids. The pegmatite hosts a diverse assemblage of rare-element mineral phases due to its high degree of geochemical fractionation. Trends of geochemical fractionation of individual mineral phases such as K-feldspar, muscovite, garnet, apatite, beryl, spodumene, triphylite-lithiophilite, tourmaline, cassiterite, and columbite-tantalite were attained via instrumentation assay. These trends illustrate an enhanced degree of magmatic differentiation relative to other pegmatites in the area.