Placid Vivianite
Placid Vivianite (#10BEBC) is a true cyan with a vibrant character. It holds its own as a focal accent, carrying visual weight without tipping into neon territory. Its HSL profile (179°, 84%, 40%) places it in the highly saturated band at a mid lightness. Best used in small doses, like logos, CTAs, focus rings, or highlight text, where its saturation becomes a feature rather than noise. For a confident two-color system, pair it with its complementary red. For something softer, pull in its analogous neighbors on either side of the wheel.
Etymology
Latin placidus, gentle / quiet — derived from placēre (to please). As a color modifier, placid implies a clear-and-unruffled quality where the hue carries the visual register of mirror-smooth lake-surface in windless mid-morning. Sits at the crisp-and-calm end of the grid, parallel to serene and peaceful in usage.
A hydrated iron phosphate mineral — colorless when freshly exposed, oxidizing to deep blue-green within hours of air exposure. Mined principally in Cornwall and California. The color refers to a fully-oxidized vivianite specimen: a saturated, slightly cool deep blue-green with the slight metallic luster of phosphate mineral.
Closest matches
The nearest named color in three reference sources, ranked by perceptual distance (ΔE76 in CIELAB). ΔE < 1 is imperceptible to most viewers; ΔE > 10 is clearly different. When two sources point to the same hex they’re merged into one tile; click any to open that color’s page.
Variations
Click any swatch to exploreHarmonies
Accessibility
How this color appears to viewers with the four major color-vision-deficiency types. Computed via the Machado (2009) physiologically-based model. If a tile matches the original, the color reads the same to that viewer.
The color used as foreground text against pure white and pure black, with the contrast ratio and WCAG 2.1 grade. Aim for AA (4.5:1) for body text and AA Large (3:1) for 18 pt+ headlines; AAA (7:1) is the gold standard for long-form reading surfaces.