Dust particles collected in the stratosphere that have chondritic elemental abundances provide a new form of extraterrestrial matter for laboratory study. Spectral transmission measurements from 2.5 to 25 μm of 26 such particles show that almost all have a dominant 10 μm silicate absorption feature. Twenty-two of the particles can be grouped into one of three spectral classes referred to as olivines, layer-lattice silicates, and pyroxenes after the minerals that provide the best match to the dust spectra. Measurements of large D/H enrichments and solar flare nuclear tracks confirm that at least some particles are interplanetary dust particles. The layer-lattice silicates have additional bands at 3.0, 6.0, 6.8, and 11.4 μm. A comparison of these spectral features with the infrared spectra of comets and interstellar grains is presented.
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Sandford et al. (1985) studied this question.