Stephen C. Kuehn

Tephra from ice- A simple method to routinely mount, polish, and quantitatively analyze sparse fine particles.

A method involving a graphite substrate has been developed for the mounting and analysis of sparse, fine particles from a liquid suspension to enable improved study of volcanic ash (tephra) and atmospheric dust preserved in glacial ice. Unpolished grains may be studied by scanning electron microscope-energy dispersive spectrometry (SEM-EDS) at full vacuum without the need for a conductive coating due to the close proximity of the underlying graphite. The same grains in the same relative positions may be subsequently examined in polished mounts by a variety of methods including SEM-EDS, electron probe microanalysis, laser ablation-inductively coupled plasma-mass spectroscopy, secondary ion mass spectrometry, and optical microscopy. Particles as small as 3-5 microm may be routinely and easily prepared for analysis as polished grains, and particles of significantly different sizes may be exposed simultaneously. The general approach also offers significant flexibility, including both single- and multiple-sample mounts, and may be adjusted to suit a variety of samples and analytical methods.