This report presents results of specific gravity and oil yield determinations made on a series of oil shale samples from a core drilled completely through the mineable oil shale beds at the Demonstration Mine near Rifle, Colorado, and from a core through the corresponding beds in the Cathedral Bluffs area. Algebraic equations for the specific gravity oil yield relationships and tables giving the volume weight oil yield relationships are presented for use in estimating oil shale reserves for the areas. Since this is the first specific gravity oil yield study to be made on a single core drilled completely through the mineable beds at Rifle, it is more comprehensive than any which has appeared previously and should supersede previously reported data for the Rifle area.