For what commercial purpose?It was a chance to trace the basinal brines that lead to the emplacement of the deposits. As simple as that. That's the kind of stuff one does for graduate work.
The idea was that overlying some of these deposits the kerogen that was dispersed in the shales may show signs of successive pulses of hot basinal brines. This should show up in paths of higher thermal maturity. In my case I was mostly looking at the various indicators of thermal maturity (increased C=C bonds in the IR or loss of C-H functional groups). There are other means as well that have been utilized, like illite crystallinity.
The goal is to determine what mechanisms were in place to account for the Pb Zn mineralization. One of the coolest papers I found was looking at the changes in galena crystallography as different fluids pulsed in with different chemical features causing a change in added layers of galena on galena crystals in these formations.
It's a neat application of organic geochem. Later on I worked extensively with coal and tracked thermal maturation using IR but also looking at things like vitrinite reflectance (a pretty standard technique) for applications using coal, not for coal exploration. That was what pushed me ultimately over into straight-up chemistry. I was spending most of my time making materials from coal and chemically treating it to see how it altered it. The same sort of stuff can be done when looking at intrusions near coal beds (or presumably any dispersed organic). In the case of intrusions near a coal bed there's thermal markers in the coal that occur both optically (vitrinite reflectance) and chemically.