Evidence for subsolidus quartz-coesite transformation in impact ejecta from the Australasian tektite strewn field

•SEM and μRaman analysis reveal coesite plus PDF-bearing quartz intergrowths.•TEM shows that quartz is in direct contact with euhedral coesite grains.•These observations indicate solid-state quartz-to-coesite transformation.•Recurrent iso-orientation with [11¯1]* of quartz parallel to [0 1 0]* of coesite.•Martensitic structural shifting of 1¯011 quartz planes into coesite (0 1 0) planes.