C

The ε-phase in high-copper dental amalgam is the copper–tin compound Cu3Sn; studies of high-copper alloys consistently list Cu3Sn as the “epsilon (ε)” constituent, distinct from the η-phase Cu6Sn5 and the γ phases of Ag-Sn or Ag-Hg [Mahler & Adey, 1984, PMID 6588080].