The Glacier de Bionnassay Italien arises from a cirque between the south eastern side of the Aiguille de Bionnassay, the Col de Bionnassay and the Calotte des Aiguilles Grises. It descends south-south west for 2.5 km below the Col Infranchissable, then turns south-east to merge with other glaciers, thence continuing as the Glacier du Miage (Ghiacciaio del Miage) - a total distance of approximately 9 km, forming the longest glacier in Italy.