Eudialyte has been defined as a silicate of Na, Ca, Fe, and Zr, with hydroxyl and Cl. Eucolite is considered to be a variety with Ce and Me. Considerable uncertainty exists, however, as to the chemistry of the two minerals. The only consistent difference was in the optic sign, eudialyte being uniaxial positive and eucolite uniaxial negative. Samples of syenite rock from Pontiac County, western Quebec, and from Seal Lake area, Labrador, were analyzed. Vivid pink granular aggregates of a vitreous silicate mineral in the former sample were identified as eucolite, and fine-grained vitreous red-dish-pink material in the latter was identified as eudialyte. No published data has been found on Canadian occurrences of these minerals. In the hand specimen they could be mistaken for garnet.