Ag 3 Au(Se 1-x Te x ) 2 alloys with the tellurium fraction x = 0, 0.1, 0.25, 0.4, 0.5, 0.6, 0.75, 0.9, and 1 were synthesized from elemental powders of Ag (99.9% metals basis), Au (99.98% metals basis), Se (99.9999% metals basis) and Te (99.8% metals basis). Powders were mixed together in respective stoichiometric ratios and sealed in evacuated silica ampules. Sealed ampules were annealed at 800 • C for 24 hours, followed by a slow cooling to room temperature over 24 hours. The final ingot products were finely ground and characterized by powder X-ray diffrac-tion (PXRD) using a Bruker D8 diffractometer with a Cu X-ray source in reflection geometry. Diffraction patterns were refined by Rietveld method using GSAS-II. We measured the electrical resistivity of the alloy samples using Quantum Design Physical Property Measurement System (PPMS) Electrical Transport Option (ETO). Temperature sweep measurements were conducted from 300 K down to approximately 118-235 K, at which point the sample resistivity exceeded the measurement range of the instrument. Sample ingots were polished into rods to facilitate straightforward dimensional measurements. We used 2-and 4-contact probe method for samples with x = 0-0.4 and x = 0.5-1, respectively, due to the magnitude of resistivity each method could accommodate. Corresponding Arrhenius plots were generated (R 2 > 0.98) using the activation law and are available in supplemental materials. Diffuse reflectance measurements were carried out using a Varian Cary 5G ultraviolet-visible-near-infrared (UV-Vis-NIR) spectrophotometer across a spectral range of 200-3000 nm. Non-diluted Ag 3 Au(Se,Te) 2 powders were used with a Spectralon pellet from Harrick Scientific Products as the reference standard.