Images of volcanic samples at various stages of preparation from macro to micro scales.

Left: Example of tephra deposits as they appear in the field. At this macro step, field geologists take notes and make detailed descriptions of the samples before collecting material for further study. Middle: A laboratory-prepared mount of volcanic glass in clear epoxy that has been polished for geochemical analysis. Right: A microscopic view of one of the volcanic glass grains from the middle photo (outlined in red), taken using a high-powered microscope. USGS Photos by K.J. Lynn.