Abstract
Diffuse reflectance spectroscopy and colorimetry have been applied to study the colors of powdered granitic rocks with different degrees of weathering. As a result, FeO(OH) was considered to be the source of the yellow-brownish color of the weathered rock powders. FeO(OH) contents were determined by diffuse reflectance spectroscopy based on the Kubelka-Munk function and found to increase during weathering. The FeO(OH) contents can be hence taken as a quantitative indicator of the degree of weathering.
