(from Wikipedia) because my feldspar hand sample identification sucks.
I am a process person. How did this landscape come to be, and how may it affect the people living nearby? To go back to petrology, what does this particular mineral assemblage tell us about the conditions under which the rock formed? Closer to my own grad school and work experience, if something nasty is spilled in this area and percolates into this bedrock, where does it go and how does it change as it comes into contact with various materials?
It’s not as simple (or as impressive to non-geologists) as picking up a rock and saying, “Of course! It’s a porphyritic granite with some lovely smoky quartz!” But I’ve always been intrigued by complications.