Just saw this impressive sliding door/wall over on Dwell. The Belgian architects 51N4E choose 5mm-thick white marble mounted on a 20mm honeycomb structure for the sliding door that separates the kitchen and adjacent storage space. The wall appears either opaque or translucent depending on time of day and amount of light.
More pictures below.
(view from storage space looking into kitchen)
To see full article at Dwell: Flemish Farmhouse Kitchen