The aim of this paper is to give a new way of phosphate deposits prospection using in situ monazite dating. U-Th–Pb data for a single grain of monazite from locality Kamenne Doly Quarry were combined with previously obtained monazite ages from Pisek pegmatites and their GPS positions (
) were processed by a MATLAB script to define region of monazite or phosphate occurrence. At least 3 assumptions have to be made. Monazites are of similar ages, are products of an extensive geological event affecting a significant amount of rock bodies in a region and the shallow rock environment is the same at different depths.