Mine　tailings-based　geopolymers　were　prepared　at　ambient　temperature.　The　evolution　of　their　microstructure　and　the　immobilization　of　lead　were　studied.　Characterizations　include　measurements　in　compressive　strength,　scanning　electron　microscope　(SEM),　Fourier-transform　infrared　spectroscopy　(FTIR),　nuclear　magnetic　resonance　(NMR)　and　toxicity　characteristic　leaching　procedure　(TCLP)　tests.　With　increasing　the　ratio　of　metakaolin　from　0%　to　50%,　geopolymer　gel　in　the　mine　tailings-based　geopolymers　increased　from　33.92%　to　79.45%,　leading　to　the　compressive　strength　that　increased　from　2　to　15.5　MPa.　With　addition　of　Pb(NO3)2,　a　three-stepped　changes　in　the　compressive　strength　and　microstructure　of　the　geopolymers　were　observed.　As　increasing　Pb(NO3)2　dosage　from　0%　to　6%,　geopolymer　gel　was　kept　constant,　while　lead　silicate　glass　increased　from　0%　to　10.51%,　and　Si　sites　in　calcium　silicate　hydrate　(CSH)　gel　decreased　from　20.55%　to　11.3%.　Pb2+　was　effectively　immobilized　in　the　geopolymers.　This　study　first　presents　the　evolution　of　geopolymer　gel,　belite,　lead　silicate　glass,　and　CSH　gel　in　mine　tailings-based　geopolymers　as　the　functions　of　metakaolin　and　Pb(NO3)2　additions.　©　2018　The　American　Ceramic　Society