Table 4.

Assignment of Complex Refractive Indexes to Particle Phases: Seattle Particles

Particle	Material Phase		Percent Volume	Complex Refractive Index Real Part	Imaginary Part	References
S1	Single phases	Goethite	96.6	2.46	0.09	Anthony et al. [2016] and Bedidi and Cervelle [1993]
		Limonite	96.6	2.46	0.0042	Anthony et al. [2016] and Egan and Hilgeman [1979, Table V-16]
		Sodium hydrogen carbonate (Nahcolite)	1.36	1.58	∼0	Anthony et al. [2016]
		Gypsum	1.00	1.53	∼0	Anthony et al. [2016]
		Soot	0.66	1.95	0.79	Bond and Bergstrom [2006]
		Graphite	0.43	2.65	1.39	Stagg and Charalampopoulos [1993]
S2	Single phases	Albite	95.5	1.57	0.000035	Anthony et al. [2016] and Egan and Hilgeman [1979, Table V-10]
		Gypsum	3.42	1.53	∼0	Anthony et al. [2016]
		Goethite	1.12	2.46	0.09	Anthony et al. [2016] and Bedidi and Cervelle [1993]
		Wustite	1.12	2.42	0.64	Henning et al., 1995
	Combined phasesa	Albite + Gypsum + Goethite	100	1.547	0.000734	Anthony et al. [2016], Egan and Hilgeman [1979, Table V-10], and Bedidi and Cervelle [1993]
		Albite + Goethite + Gypsum + Goethite(inclusion)	100	1.618	0.00643
		Albite + Gypsum + Wustite	100	1.547	0.00506	Anthony et al. [2016], Egan and Hilgeman [1979, Table V-10], and Henning et al. [1995]
		Albite + Wustite + Gypsum + Wustite(inclusions)	100	1.607	0.0378
S3	Single phases	Calcite	31.3	1.49	∼0	Anthony et al. [2016]
		Anorthite	26.3	1.59	0.000035	Anthony et al. [2016] and Egan and Hilgeman [1979, Table V-10]
		Wustite	21.9	2.42	0.64	Henning et al. [1995]
		Goethite	21.9	2.46	0.09	Anthony et al. [2016] and Bedidi and Cervelle [1993]
		Limonite	21.9	2.46	0.0042	Anthony et al. [2016] and Egan and Hilgeman [1979, Table V-16]
		Gypsum	20.5	1.53	∼0	Anthony et al. [2016]
	Combined phasesa	Calcite + Anorthite + Wustite + Gypsum	100	1.731	0.112	Anthony et al. [2016], Egan and Hilgeman [1979, Table V-10], and Henning et al. [1995]
		Calcite + Anorthite + Goethite + Gypsum	100	1.722	0.0156	Anthony et al. [2016], Egan and Hilgeman [1979, Table V-10], and Bedidi and Cervelle [1993]
		Calcite + Anorthite + Limonite + Gypsum	100	1.722	0.000731	Anthony et al. [2016] and Egan and Hilgeman [1979, Tables V-10 and V-16]

^aOptical properties for combined phases are calculated from Maxwell-Garnett dielectric function (see equations (1)–(3)). The real part of the Maxwell-Garnett function ε′ = n² – k², where n and k are the real and imaginary parts of the refractive index. Likewise, the imaginary part of the Maxwell-Garnett function ε″ = 2nk.