We observed interesting amphibole morphologies by transmission electron microscopy (TEM) in air samples collected by the United States Environmental Protection Agency (USEPA) in Libby, Montana. Individual amphibole particles were identified and photographed on approximately 200 randomly selected air samples. Transfer of the TEM grids and relocation of these amphiboles in the field emission scanning electron microscope (FESEM) produced high-resolution secondary electron images that allowed a closer examination of these particles. Some of the amphiboles were perfect euhedral single crystals (several micrometers long and 200–500 nanometers wide) showing the classic {110} forms, while other single crystals appeared to be attached to sheet silicates and yet others appeared to have “wings” or “fins,” often less than one micrometer in width, attached to their edges. Energy Dispersive X-Ray Spectroscopy (EDS) and selected area electron diffraction (SAED) from the TEM confirmed that these particles were intergrown amphiboles and sheet silicates. Soil samples collected by the USEPA in Libby, Montana were also analyzed. FESEM investigation revealed that the soil samples contained amphiboles with the same morphologies as observed in the air samples, and were also intergrown with sheet silicates. Thus, these amphiboles occur as single crystals between the layers of vermiculite and hydrobiotite.

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