Collection of Stratospheric Microparticles Above the Sulfate Layer Using Balloon-Borne Collectors

We report preliminary analytical electron microscope (AEM) analysis of nearly 300 stratospheric particles collected using balloon-borne collectors at 34–36 km altitude. The particles are predominantly silica, plagioclase feldspar, Mg, Fe-silicates and rare barite, metal oxides, and unidentified Fe, Ni, Zn, and Pb particles. The majority of these generally submicron-sized particles are comparable to volcanic particles collected at 20 km altitude from the 1982 eruption of the El Chichon volcano. Because of the uniqueness in altitude and collected particle sizes the collection may also contain interplanetary dust particles of types poorly represented in present collections.