The Mount Hope kaolin deposit on SW Eyre Peninsula was formed by deep weathering of granite gneiss and schist, probably Sleaford Complex. The deposit has been investigated since 1972 as a potential source of high-grade kaolinite suitable for coating paper. Kaolin was formed from alteration of feldspar and mica and shows a variety of morphologies. Non-kaolin minerals were predominantly quartz with minor mica and rutile / anatase and trace amounts of iron oxides and a rare earth phosphate. Particle size separation by sedimentation produces a 2 micro-metre fraction with a high proportion of thin kaolinite platelets 2-10 micro-metres in diameter. Rolled flakes or tubular forms are present in trace or minor amounts in all samples but comprise 20% of 1 sample.