A scanning electron microscope (SEM) image and an elemental map of an alunite (a mineral) crystal found in the hydrothermal plume above NW Rota-1 volcano. The upper left box is the image. The remaining boxes are elemental maps of the elements indicated. The graph at the bottom of the image is a spot x-ray analysis of the particle. (Al stands for aluminum, Na is sodium, K is potassium, and S is sulfur.)
