gsminmag Mineralogical Magazine Mineralogical Magazine 0026-461X Mineralogical Society 10.1180/minmag.1964.033.264.02 Olivine Composition Determination with Small-Diameter X-Ray Powder Cameras1 Jambor J. L. Smith Charles H. Geological Survey of Canada, Ottawa

Canadian Contribution No. 3 to the International Upper Mantle Project.

 3 1964 33 264 730 741 Copyright © 1964, The Mineralogical Society 1964 Summary

Olivine composition can be rapidly and accurately obtained by using standard (Straumanis-mounting) 57·3 mm X-ray powder cameras. A determinative curve based on analysed natural olivines has been constructed by plotting the mol. % Fo against the spacing of back-reflection line 174. The regression equation for the composition range Fo100 to Fo30 is

Fo (mol. %) = 4151·46−3976·45 d174

using Fe-Kα1 radiation. The fayalite end (Fo30 to Fo0) of the determinative curve shows a relatively sharp break from a straight-line relationship of d-spacing versus composition. Practical applications of the determinative curve are briefly presented.