Now I return to the lab to study the pumice. This is where my research really begins! These rocks formed over thousands of years under extreme temperatures and pressures. My goal is to figure out exactly how they formed. To do this, I'm going to crush a piece of pumice and try to re-create it in the lab. I have to learn as much as I can about the rock before I begin. I'm most interested in two parts of the pumice: volcanic glass and melt inclusions Volcanic glass is magma that cooled quickly after it erupted. It has the same composition as the original magma, minus gases that escaped.   Down in the magma chamber, sometimes drops of melt, or magma, get trapped inside minerals as they grow. When the magma erupts and cools, these melt inclusions remain intact and preserve droplets of the original magma, including the gases. My scientific assistant Christine Tappen does most of the work to get the samples ready. She also helps to analyze them. To begin, we prepare the samples. To get a closer look, we cut a rock into thin slices or crush it and separate the grains. Then we mount the samples on glass slides. Then, we examine them. We're looking for rock samples with minerals that contain melt inclusions. These can only be seen with a powerful microscope because they are smaller than a grain of sand. We also use more powerful instruments to measure the amount of and types of gases in the samples. Now I know a lot about the pumice. I'm ready to begin my experiments.