Eos, Transactions American Geophysical Union

Volcanic dust particle reveals growth pattern under microscope


  • Anonymous


The photograph shows a sample particle of volcanic ‘dust,’ enlarged 533 times, which was collected recently at the site of the Mount St. Helen's eruption. The chemically zoned structure—resembling the ‘growth-ring’ pattern of a tree — indicates that during crystal growth the particle was probably subjected to varying pressures and temperatures as it was formed in the magma inside the volcano. Microscopists A. S. Holik and D. G. Fink at the General Electric Research and Development Center prepared a polished thin slice of the particle and photographed it through a microscope which used transmitted polarized light.