The Miroir d'Argentine isn't a real summit. It's more of a face between the summit of the Cheval Blanc 2323 m (West) and the Haute Corde 2325 m (East). I use the name 'Miroir d'Argentine' because it is far more common and well known.
First ascent of the Miroir d'Argentine: F.Delisle, Ch. Rathgeb 1926