Spectral Arch Turquoise

Latin spectrum, appearance — adjectival suffix -al. As a color modifier, spectral implies a saturated-and-rainbow-decomposed-and-pure quality, the bright color of Newton-prism sunlight-decomposed seven-color spectrum band. Sits at the bright-and-pure end of the grid, parallel to prismatic and pure in usage.

Latin arcus, bow / curve. As a color modifier, arch implies a Roman-and-Gothic-and-Romanesque-vault quality, the visual register of Roman-aqueduct-and-Romanesque-cathedral hand-cut stone-and-brick voussoir-and-keystone arch-and-vault architectural surfaces under monumental architecture light. Sits at the modifier-and-architecture end of the grid, parallel to dome and vault in usage.

The hydrated copper-aluminum phosphate mined in Persia and the American Southwest for thousands of years — the firuze of Iran, the chalchihuitl of Mesoamerica, the heart of Pueblo and Navajo silverwork. The color refers to a fine Sleeping Beauty turquoise from Arizona: a saturated, slightly green-shifted blue with the slight matrix of host-rock veining. Brighter than persian, lighter than cerulean.