THE name ‘huttonite’ is proposed for a newly recognized monoclinic mineral of the composition ThSiO4. It has been isolated in minute grains from beach sand of South Westland, New Zealand, by Prof. C. Osborne Hutton, of Stanford University. Its optical properties are: α= 1.898, β= 1.900, γ = 1.922; dispersion ρ > γ, moderate; 2V = 25° (measured); Y || b, Z near c; colourless to very pale cream. X-ray study by means of powder, rotation and Weissenberg patterns shows that huttonite is isostructural with monazite. Space group C2h5 – P21/n; a0 = 6.80A., b0 = 6.96A., c0 = 5.54A., β = 104° 55′. The measured density is 7.1 ±0.1. The calculated density, corresponding to a cell content of 4(ThSiO4), is 7.18.