Hot rocks: Constraining the thermal conditions of the Mistastin Lake impact melt deposits using zircon grain microstructures

•Further evidence for superheating reaching temperatures >2370°C discovery in an impact glass sample.•First occurrence of FRIGN zircons and high-pressure polymorph reidite at the Mistastin Lake impact structure.•Evidence for superheating appears to only be preserved in glass-bearing impactites.•Mistastin Lake zircon and zirconia microstructures provide insight for P-T conditions at other terrestrial craters.