Monoclinic palygorskite with the unit cell a0 = 12.689 Å, b0 = 17.845 Å, c0 = 5.119 Å and ß = 91.22° has been found at Padasjoki, southern Finland. The mineral is thought to be of hydrothermal origin. Monoclinic symmetry is connected with an ordered Mg-Al substitution, although owing to the low Δd121‒121 value observed a low degree of ordering is suggested.