AbstractA chrysotile disc is proposed as the fundamental seed structure for the formation of chrysotile asbestos fibres, polygonal serpentine fibres and polyhedral lizardite spheres. The curvature, fivefold symmetry and hydrogen-bonding alignment of the layers in the seed disc control the formation of the 15 or 30 sectors in polygonal serpentine and the orientations of the planar arrays of 15 or 30 radial crystals in polyhedral serpentine. A polygonized disc precursor to polygonal fibre formation has been observed at an arrested stage of growth in a synthesis experiment.