Possible approaches in the application of a hand-held X-ray fluorescence analyzer for the study of marl raw materials have been demonstrated. Chemical indicators relating the chemical and phase compositions of the studied objects are derived. This has been done on the basis of an analysis of preliminary laboratory investigation results (chemical analyzes and powder X-ray diffraction) of marl and clay samples of varying ratios of their constituents – clayey, carbonate and possibly terrigenous. Such indicators allow rapid collection of relatively reliable data in the study of marl raw materials in field conditions and subsequent sampling of materials with desired phase-chemical characteristics, even within a single locality.