We have analysed in detail the geometry of the I-WP infinite periodic minimal surface, discovered by Alan Schoen in the 1960's. An exact parametrisation has been found, using the local Weierstrass equations for the surface, involving modified hyperelliptic integrals. We have used rapidly converging integration techniques to calculate the surface to volume ratio of this surface, and found that it differs from the value conjectured by Anderson. Further, the family of isometric minimal surfaces related to the I-WP surface has been found to exhibit a novel sequence of structures ; viz. repeated formation of the I-WP surface itself.On analyse en détail la géométrie de la surface minimale infinie et périodique I-WP, découverte par Alan Schoen dan...