Scanning Electron Microscope (SEM) image and elemental map of an alunite 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 = Aluminum, Na = Sodium, K = Potassium, and S = sulfur.)
