Pasco (/ˈpæskoʊ/ PAS-koh) is a city in, and the county seat of, Franklin County, Washington, United States. The population was 77,108 at the 2020 census, and 79,315 as of the July 1, 2022 estimate.
Pure copper is orange-red and acquires a reddish tarnish when exposed to air. This is due to the low plasma frequency of the metal, which lies in the red part of the visible spectrum, causing it to absorb the higher-frequency green and blue colors.