Open Castor Mint

Old English open, unobstructed — used as a color modifier since the eighteenth century for hues that read as airy or uncrowded. Open blue, open green: moderate saturation combined with optical spaciousness, the slight visual breath of a hue that doesn't crowd the surface it covers. Sits at the crisp-bucket center alongside clear.

Greek Κάστωρ, Gemini-twin-and-horseman. As a color modifier, castor implies a Gemini-twin-and-mortal-brother quality, the visual register of Gemini-Castor-and-Pollux-twin hand-Gemini-twin-and-mortal-brother Gemini-Castor-and-Pollux-twin-and-Argonaut castor-and-Gemini-twin-and-mortal-brother surfaces under Gemini-Castor-and-Pollux-twin-and-Argonaut spring-Gemini-and-Bortle-1-sky stellar-twin-light. Sits at the modifier-and-cosmic end of the grid, parallel to pollux and spica in usage.

The genus Mentha — peppermint, spearmint, apple mint, water mint — the cooling herb whose menthol gives it that quality at the molecular level. The color refers to fresh peppermint leaves before drying: a clean, slightly cool green with the matte finish of trichome-rich leaf surface. Lighter than basil, cooler than parsley, with the mojito-and-Pimm's association of a herb tied to summer drinks across two continents.