Inclusions can be particularly useful in the petrological and volcanological studies. Guppy was appointed to the Petrological Department. Ijolite is a rare rock type of considerable importance from a mineralogical and petrological standpoint. Results are compared with petrological experimental results for validation. Petrological and geochemical results provide indisputable evidence for supporting a mantle plume origin. After moving to Dublin he worked on "foraminifera" and brachiopods, before switching to petrological work. Petrological techniques can be applied to pottery and bricks. Petrological indicators of UHP metamorphism are usually preserved in eclogite.