Onyx
Onyx is a translucent, banded calcite or aragonite stone with a density of 2.7 g/cm³, supplied as polished slabs, aragonite varieties, resin- and mesh-backed panels and glass-laminated veneers.
Reference datasheet — Onyx is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Onyx tempers and conditions
Onyx is supplied in one standard condition, ARAG.
Supply forms, finishes and certifications
Ways Onyx is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
RESIN-MESH | Epoxy-impregnated, fibreglass mesh-backed slab | Supply form |
SLAB-POLDefault | Calcite onyx, sawn and polished slab | Supply form |
LAM-GLASS | Thin onyx veneer laminated to glass or aluminium honeycomb | Surface finish |
What is Onyx?
Onyx is a translucent, banded calcite or aragonite stone with a density of 2.7 g/cm³, supplied as polished slabs, aragonite varieties, resin- and mesh-backed panels and glass-laminated veneers. Engineers and designers specify it for light transmission and decorative veining; its low hardness (machinability score 65) makes CNC routing, waterjet inlay and hand carving straightforward. The limits are structural and chemical: banding planes split easily, service temperature is about 150 °C, and the carbonate matrix etches on contact with acids. Marble is the nearest alternative where translucency is not required. Onyx has a density of 2.7 g/cm³ (0.0975 lb/in³), heavier than 93% of natural material grades. Onyx has a tensile strength of 6 MPa (0.87 ksi), weaker than 81% of natural material grades. The elastic modulus is 50 GPa (7.25 Msi).
What is Onyx used for?
- Backlit wall panels
- Decorative countertops
- Sculptures and vases
- Feature lighting elements
Advantages
- Polishes to a fine finish — 88/100, better than 94% of natural material grades
- Conducts heat well — 2.3 W/m·K (1.33 BTU/hr·ft·°F), better than 91% of natural material grades
- Stiff — 50 GPa (7.25 Msi), better than 88% of natural material grades
- Low embodied carbon — 0.22 kg CO₂/kg, better than 84% of natural material grades
Limitations
- Heavy — 2.7 g/cm³ (0.0975 lb/in³), worse than 93% of natural material grades
- Needs corrosion protection — 22/100, worse than 93% of natural material grades
- Difficult to machine — 65/100, worse than 81% of natural material grades
Onyx properties
Typical room-temperature values; bars are the position among natural material grades.
Physical2
Onyx has a density of 2.7 g/cm³ (0.0975 lb/in³), heavier than 93% of natural material grades.
Mechanical11
Onyx has a tensile strength of 6 MPa (0.87 ksi), weaker than 81% of natural material grades. The elastic modulus is 50 GPa (7.25 Msi).
Thermal5
Onyx is rated for continuous service to 100°C (212 °F). It conducts heat at 2.3 W/m·K (1.33 BTU/hr·ft·°F), better than 91% of natural material grades. Thermal expansion is 8 µm/m·K (4.44 µin/in·°F).
Electrical1
Onyx has an electrical resistivity of 1,000,000 Ω·m.
Chemical & Environmental1
Corrosion resistance is poor (22/100), worse than 93% of natural material grades.
Sustainability4
Producing a kilogram of Onyx takes about 3 MJ of energy and emits 0.22 kg of CO₂ — less than 84% of natural material grades. Typical recycled content is 0%.
Manufacturability2
Onyx's machinability is good (65/100, worse than 81% of natural material grades).
Common Calculations4
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Working with Onyx
Is Onyx easy to machine?
Cut wet with continuous-rim diamond blades and light feed; the stone is soft but splits along banding, so support the slab fully and avoid dry cutting or hammer drilling.
Can Onyx be welded?
Not weldable — sections are joined with epoxy/polyester colour-matched adhesive or mechanical anchors, with mitred and glued corners for boxes and vanities.
Can Onyx be formed, bent or molded?
Shaping is subtractive only: CNC routing, waterjet inlay and hand carving all work well because of the low hardness; thin translucent veneers are laminated to glass or honeycomb rather than bent.
Onyx chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| CaCO3calcite or aragonite; source of translucency and acid sensitivity | 92 – 99.5 | 97 |
| MgCO3 | 0.1 – 3 | 0.8 |
| SiO2detrital quartz/chalcedony | 0.05 – 2.5 | 0.5 |
| Fe2O3iron oxide — honey/amber and red banding | 0.02 – 1.5 | 0.3 |
| Al2O3clay impurity | 0.02 – 1 | 0.2 |
| MnO + Cu/Cr tracesgreen and pink colouration | 0 – 0.3 | 0.05 |
| other (impurities, bound water) | balance |
What surface finishes work on Onyx?
Takes a very high polish with cerium/tin oxide, but must be impregnated with a solvent-based penetrating sealer and kept away from acids; honed or leathered finishes hide etch marks better in wet areas.
How much does Onyx cost?
Onyx is a standard-cost natural material ($$), cheaper than about 71% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Onyx — frequently asked
What is Onyx used for?
Onyx is typically used for backlit wall panels, decorative countertops, sculptures and vases and feature lighting elements. In short: translucent decorative stone; soft, easily carved; acid-sensitive, needs sealing.
What is the tensile strength of Onyx?
Onyx has a typical tensile strength of 6 MPa (0.87 ksi) — weaker than 81% of natural material grades.
Is Onyx easy to machine?
Reasonably — machinability is rated good (65/100, worse than 81% of natural material grades). Cut wet with continuous-rim diamond blades and light feed; the stone is soft but splits along banding, so support the slab fully and avoid dry cutting or hammer drilling.
Can Onyx be welded?
Not weldable — sections are joined with epoxy/polyester colour-matched adhesive or mechanical anchors, with mitred and glued corners for boxes and vanities.
What surface finishes work on Onyx?
Takes a very high polish with cerium/tin oxide, but must be impregnated with a solvent-based penetrating sealer and kept away from acids; honed or leathered finishes hide etch marks better in wet areas.
Can Onyx be formed, bent or molded?
Shaping is subtractive only: CNC routing, waterjet inlay and hand carving all work well because of the low hardness; thin translucent veneers are laminated to glass or honeycomb rather than bent.
What is the maximum service temperature of Onyx?
Onyx is rated for continuous use to about 100°C (212 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does Onyx cost?
Onyx is a standard-cost natural material ($$), cheaper than about 71% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- ASTM C503 — Standard Specification for Marble Dimension Stone — ASTM International (2018)
- ASTM C97/C99/C170/C880 — absorption & density, modulus of rupture, compressive and flexural strength of dimension stone — ASTM International (2018)
- Dimension Stone Design Manual — Natural Stone Institute (formerly MIA+BSI) (2016)
- Handbook of Physical Constants — elastic and thermal properties of carbonate rocks — Geological Society of America (1995)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.