Firm Sphalerite
Firm Sphalerite (#6B900D) is a deep lime with a jewel character. It carries the deep, saturated richness of a gemstone. Authoritative and slightly formal, it works well for type and heavy UI elements. Its HSL profile (77°, 83%, 31%) places it in the highly saturated band at a dark 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 indigo. For something softer, pull in its analogous neighbors on either side of the wheel.
Etymology
Latin firmus, strong / stable — sharing root with English farm (originally a fixed-yearly-rental). As a color modifier, firm implies a saturated-and-resolute quality where the hue holds its visual position without wavering. Sits at the bold-and-firm end of the grid, parallel to steadfast and unwavering in usage.
A zinc sulfide mineral — both an important zinc ore and a high-dispersion gem with adamantine luster. The yellow variety is mined principally in Spain and Mexico. The color refers to a faceted yellow Spanish sphalerite: a saturated, slightly cool yellow-orange with the gem's signature internal fire (higher dispersion than diamond).
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.