Spectral emission polarization of quartz and calcite polished plates for observation angles of 20° and 70° is calculated by the substitution of complex index of refraction values for each mineral into Fresnel’s equations. The emission polarization is shown to be quite wavelength-dependent, demonstrating that selected narrow or medium-width (Δλ ≈ 1.5 μm) spectral bands exhibit a significantly higher percentage of polarization than a broad spectral band (Δλ ≈ 6 μm) for these two minerals. Field measurements with a broadband infrared radiometer yield polarizations on the order of 2% for a coarse-grained granite rock and beach sand (both quartz-rich). This implies that a more sensitive detector with a selected medium-width filter may be capable of measuring emission polarization accurately enough to make this parameter useful as a remote sensing tool for discrimination among rocks on the basis of texture.
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