Aerosoolides

Aerosoolides are a proposed class of nanoscale airborne particles that resemble mineral grains in morphology but form within atmospheric aerosols. They are typically hollow or porous spheres composed of metal oxides and silicates, often with organic surface coatings, and they commonly measure tens to a few hundred nanometers in diameter. The name merges aerosol origin with the -oid suffix used for resemblance to mineral grains.

The term aerosoolide was introduced in atmospheric science literature in the early 2020s to describe a recurring particle morphology observed in diverse plume environments. Researchers began treating aerosoolides as a descriptive category rather than a single mineral species, reflecting their variable composition and formation pathways.

Formation and occurrence occur through high-temperature processes and atmospheric aging. They can originate from combustion and metal-vapor condensation, with secondary processing in the atmosphere promoting coating by organic matter. Aerosoolides have been detected in urban PM2.5, wildfire smoke plumes, and volcanic eruptions, and may form in industrial settings where metal-containing vapors are produced.

Physical and chemical properties are variable but share key traits: nanoscale size, hollow or porous spherical structure, and a composition that often includes iron, silicon, calcium oxides, or mixed metal oxides, accompanied by organic carbon coatings. They are identifiable by transmission electron microscopy and spectroscopic techniques such as energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy, which reveal core–shell or porous morphologies and elemental makeup.

Significance lies in atmospheric chemistry and climate effects, including light scattering and potential roles as cloud condensation nuclei. Health implications are an area of ongoing study. Aerosoolides are not formally recognized as mineral species; they serve as a descriptive category within aerosol science, with potential subtypes defined by dominant composition.