Rudimentary Basalt
Rudimentary Basalt (#2B3639) is a deep cyan with an earthy character. It leans grounded and natural, the kind of color that plays well with wood, clay, linen, and warm neutrals. Its HSL profile (193°, 14%, 20%) places it in the muted band at a dark lightness. It works well as a headline, icon, or deep background in an otherwise light layout, pairing cleanly with cream, bone, and warm neutrals. 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 rudīmentum, first principle — adjectival suffix -ary. As a color modifier, rudimentary implies a neutral-and-basic-and-stripped-down quality where the hue carries the visual register of prehistoric-and-cave-art rudimentary-and-foundational-mineral-pigment color-decision. Sits at the neutral-and-foundational end of the grid, parallel to basic and primal in usage.
The fine-grained volcanic rock formed when basaltic lava cools rapidly at the surface — the dominant rock type of oceanic crust and the columnar Giant's Causeway in Northern Ireland. The color refers to a freshly cut basalt slab: a soft, slightly muted gray-black with the matte finish of fine-grained igneous stone. Cooler than asphalt, deeper than slate, with the geological weight of the rock that paved Neapolitan streets and the seafloor of the Atlantic.
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.
Wide gamut
The CSS Color 4 wide-gamut form of this color. Both swatches render the same color on every display — the P3 form only diverges from sRGB when a designer pushes channels outside sRGB's reach.
This color sits well within the sRGB cube. P3 and sRGB share the gray axis and most desaturated tones, so a P3 display renders this identically to an sRGB display.