In Guaviare Department (Eastern Colombia) isolated outcrops of Ediacaran peralkaline nepheline syenites (∼577 My) have been reported which could have strong implications to our understanding of Amazonian Craton evolution during this time and a possible genetic association with REE deposits. This paper includes the petrographic and geochemical characterization of 19 rock samples from the San Jose del Guaviare Nepheline Syenite outcropping in the vicinity of El Capricho and La Cristalina using Transmitted-Light Microscopy, RAMAN Spectroscopy and X-Ray Fluorescence, correlating new results with previously published data from Jordan, La Pizarra and Las Delicias (a total of 55 samples). Analyzed samples are coarse-grained to pegmatitic commonly displaying foliated textures (shear deformation) with minerals like alkali feldspars (Mc,Or), feldspathoids (Ne, Ccn,Sdl), Arf, Ttn and Bt being classified as Nepheline Syenites, Juvites and Malignites (first report). Particularly, in La Cristalina pegmatites rare opaque minerals are present (3%) identified as Pyrochlore and linked to high concentrations of Nb, U and Th. Geochemically, samples are ferrous peralkaline and show affinity with intraplate magmatism, being interpreted as a result of a unique comagmatic event connected to the beginning of an Ediacaran-Cambrian extension phase (Iapetus Ocean?) in western margin of Amazonian Craton whose source was highly differentiated with respect to the Primordial Mantle and seem to have had a strong interaction with Continental Crust materials, consistent with the large lineaments found in the study area and the observed sub-solid-state shear deformation textures.