onyx
Black Onyx
Architectural Black Onyx is a sedimentary rock primarily composed of calcite (calcium carbonate), formed by the precipitation of calcite-rich groundwater in layers within caves or fissures. This process creates banded, translucent deposits with fine crystal growth. The characteristic jet black color is often achieved through treatment, as natural black onyx is rare and typically has faint veins or gray shading. Its cryptocrystalline structure allows for its prized translucency.
- Quarry
- Mexico; Pakistan
- Mohs hardness
- 3–4
- Water absorption
- 0.1–2%
- ASTM spec
- ASTM C503
- Installed price
- $70–$250/sq ft installed
- Slab price
- $35–$250/sq ft slab
- Finishes
- Polished, Honed, Matt
- Applications
- Backlit panels, Feature walls, Bar tops, Decorative countertops, Powder room vanities, Reception areas
- USA distributors
- Nova Tile and Stone; Acemar Stone; Sia Stones; Modul Marble; George Stone
- Maintenance
- Requires gentle care with pH-neutral cleaners; blot spills immediately as it is highly porous. Regular sealing (every 6-12 months) is crucial to reduce staining, but it does not prevent acid etching.