Isotope analysis of closely adjacent minerals

This patent describes a method of determining an indicator of at least one of hydrocarbon formation, migration, and accumulation during mineral development. It comprises: searching for a class of minerals in a mineral specimen comprising more than one class of minerals; identifying in the mineral specimen a target sample of the thus searched for class; directing thermally pyrolyzing laser beam radiation onto surface mineral substance of the target sample in the mineral specimen releasing surface mineral substance pyrolysate gases therefrom; and determining isotope composition essentially of the surface mineral substance from analyzing the pyrolysate gases released from the thus pyrolyzed target sample, the isotope composition including isotope(s) selected from the group consisting of carbon, hydrogen, and oxygen isotopes; determining an indicator of at least one of hydrocarbon formation, migration, and accumulation during mineral development of the target mineral from thus determined isotope composition of surface mineral substance pyrolysate