JMDMT #1629 Microfossils of Cyanobacteria in Carbonaceous Meteorites

The James M. DuPont Meteorite Collection -some anhydrous interplanetary dust particles (IDPs) belonging to the chondritic porous (CP) subset are of cometary origin [1]. As such, they may provide the opportunity to examine the oldest and best-preserved solids in the solar system. However, average grain sizes in CP IDPs can be as small as 5-20 nanometers, with some mineral grains containing less than 50,000 atoms [2,3]. This scale of heterogeneity presents formidable analytical challenges, but significant progress has been made using transmission electron microscopes (TEMs) equipped with lanthanum hexaboride (LaB6) cathodes and focused nanoprobes 1-3 nm in diameter. Recently, a 200-keV field emission scanning transmission electron microscope (FE STEM) was used to analyze IDP thin-sections. The FE