Abstract: Sweetite, naturally occurring Zn(OH)₂ with tetragonal symmetry, has been found at Milltown, near Ashover, Derbyshire. It occurs as colourless or whitish bipyramids up to 1 mm in size scattered over the surface of colourless fluorite cubes. The cell dimensions are α 8,222 and c 14.34Å with Z = 20. The strongest lines of the X-ray powder pattern are (d, I, hkl): 4.53 37 (112); 3.572 60 (004,202,211); 2.922 100 (213,220); 2.708 18 (105,204); 2.257 17 (224,215,321); 1.840 11 (226,420,413); 1.764 24 (316). Sweetite is uniaxial negative, ω 1.635, ɛ 1.628. D_meas is close to 3.33 and D_cale 3.41. Chemical analysis gave 84.3% ZnO and 17.0% H₂O, while theoretical figures for Zn(OH)₂ are 81.9 and 18.1% respectively.