Radon Emanation from Dust of Varying Composition and Size
$^{222}Rn$ emanating from environmental dust constitutes an important background component for many low-energy, low-rate experiments. Radon emanation rates from dust and rock, thus, are important for experiment planning. In this paper, we report measured radon emanation fractions for five types of dry dust differing in grain size and composition. These data were obtained by a novel technique in $\gamma$-spectroscopy, measuring emanated and non-emanated $^{222}Rn$ progeny activities as well as the the parent $^{226}$Ra activity in a time series. The range of observed radon emanation fractions is $(3.7 \pm 2.0)\%$ to $(16.2 \pm 0.9)\%$. Four of the five samples are standardized samples available commercially, so additional investigations of these samples may be readily carried out.