Abstract
If the GEMS (glass with embedded metal and sulfides) particles recently identified by meteoriticists are indeed examples of interstellar silicate grains, then the spacing of the embedded "superparamagnetic" (SPM) inclusions in GEMS particles appears consistent with the theory of superparamagnetic grain alignment first proposed by Jones & Spitzer. Using an SPM hypothesis, Mathis has shown that the observed wavelength dependence of the polarization of background starlight is readily explained if grains smaller than about 0.09 μm in size have no SPM inclusions. Martin has already noted that the bulk properties of GEMS particles are consistent with the SPM hypothesis, as well as with the notion that GEMS particles are interstellar grains. In this Letter we make the single point that the spatial frequency (~0.1 μm) of the SPM inclusions implied by the GEMS particles for interstellar grains is tantalizingly close to the Mathis value needed to explain the observed wavelength dependence of polarization.