Summary: A re-examination of the mineral scolecite has shown that the previously published monoclinic (pseudo-orthorhombic) unit cell is face-centred and that the Hermann-Mauguin spacegroup symbol has been incorrectly assigned. The reduced monoclinic cell yields a 9·85 Å, b 18·98 Å, c 6·52 Å, β 110° 61; space group Aa. New indexed powder data are included.