Cu deposited syngenetically in organic sediments occurs in southeastern New Brunswick, Canada, where a peat swamp contains up to 10% Cu dry weight. This Cu occurrence appears unique in that the metal is contained invisibly in subneutral to slightly alkaline peat. This contrasts sharply with the other Cu swamps described in the American geological literature in which megascopic lumps and aggregates of native Cu are found in organic sediments of acidic pH. The source of the Cu must be sought in the surrounding ground morainal deposits or in the underlying bedrock. The cupriferous solutions have the characteristics of deeply circulating waters, and enter the swamp as seepages. These water seepages, therefore, are not normal "outcrops" of the water table. The glaciology of the region indicates that the peat could not be more than 4000 years old, and this maximum age is corroborated by the estimated time required to account for the emplacement of the present tonnage of metal, assuming a constant rate of Cu deposition.