Abstract: The kerogen content of oil shale is measured by illuminating the surface of a solid piece of oil shale so that the amount of light not absorbed by the oil shale is reflected from the illuminated surface. A monochromatic portion of the reflected light is sensed, the wavelength of the sensed light being within the absorption band for kerogen in oil shale. The amount of light absorbed by the piece of oil shale is proportional to its kerogen content, and the amount of sensed reflected light, which is inversely proportional to kerogen content, is converted into a measurement of kerogen content. To avoid wide variations in measured kerogen content, caused by nonuniform kerogen distribution within the sample being analyzed, reflected light is integrated over an area of the sample likely to have numerous varves containing kerogen.

Abstract: A field instrument for measuring the chemical composition of a solid core sample includes means for forming a smooth surface along the core sample, a light source for illuminating the smoothed surface, a photocell for sensing monochromatic light reflected from the surface of the core sample, means for providing relative movement between the core sample and the photocell, and means for converting the photocell output into a measurement of the amount of a chemical component being analyzed contained in the core sample. To avoid wide variations in measured chemical content, caused by non-uniform distribution of the material being analyzed within the core sample, reflected light is integrated over a selected area of the core sample.