Onyx vs Slate
Natural Material · grade comparison
Onyx and Slate are both natural material grades. Slate is the stronger of the two: tensile strength 16 MPa (2.32 ksi) against 6 MPa (0.87 ksi) for Onyx, about 167% more. Onyx is lighter (2.7 g/cm³ vs 2.8 g/cm³ for Slate) and Slate is stiffer (65 GPa vs 50 GPa). On the shop floor, Onyx machines more easily (65 vs 55 out of 100) and Slate sits in a lower cost tier (budget, $) than Onyx (standard, $$).
OnyxChoose it when weight is the constraint, or when the part is machined in volume.
SlateChoose it when strength drives the design, or when the part sees heat.
Onyx vs Slate: propertiesHow to read these bars
- One bar per material. A full bar is the highest value among all natural material grades in the FabDigit library; each bar is drawn as a share of that.
- The better value (by the usual engineering direction) is in bold. Rows with no direction — density, thermal conductivity — have no bold.
- Values are typical room-temperature figures for the condition named on each card.
- Confirm against the certified mill or resin datasheet before design release.
How to read these bars
- One bar per material. A full bar is the highest value among all natural material grades in the FabDigit library; each bar is drawn as a share of that.
- The better value (by the usual engineering direction) is in bold. Rows with no direction — density, thermal conductivity — have no bold.
- Values are typical room-temperature figures for the condition named on each card.
- Confirm against the certified mill or resin datasheet before design release.
Mechanical
Strength, stiffness, ductility and hardness at room temperature.
Elastic (Young's) Modulus
Shear Modulus
Poisson's Ratio
Tensile Strength (Ultimate)
Compressive Strength
Flexural Strength
Shear Strength
Fracture Toughness (K_IC)
Hardness, Knoop
Hardness, Mohs
Elongation at Break
Same in both: Bulk Modulus 40 GPa5.8 Msi
Physical
Density and transition temperatures.
Density
Porosity
Thermal
How each material carries heat and how hot it can run.
Thermal Conductivity
Specific Heat Capacity
Thermal Expansion (CTE, 20–100 °C)
Max Service Temperature (continuous)
Min Service Temperature
Electrical
Conductivity and insulation.
Electrical Resistivity
Dielectric Strength
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Corrosion Resistance
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Machinability
Polishability
Sustainability
Primary-production footprint per kilogram.
Embodied Energy (primary production)
Embodied Carbon (primary production)
Embodied Water
Typical Recycled Content
Common Calculations
Ratios derived from the values above.
Specific Strength (UTS / density)
Specific Stiffness (E / density)
Same in both: Thermal Diffusivity 1 mm²/s · Thermal Shock Resistance Index 0
Strength versus weight
Yield strength against density for every natural material grade in the FabDigit library; the compared grades are highlighted. Up and left is stronger for its weight.
Manufacturing and finishing
| Capability | Onyx | Slate |
|---|---|---|
| Default condition | — | — |
| Relative cost | $$ Standard | $ Budget |
| Min. machined wall | — | — |
| Best machined surface | — | — |
Onyx vs Slate — frequently asked
Is Slate stronger than Onyx?
Yes. Slate has a typical tensile strength of 16 MPa (2.32 ksi) against 6 MPa (0.87 ksi) for Onyx — about 167% more.
Which is cheaper, Onyx or Slate?
Slate is the lower-cost material: it sits in the budget tier ($) while Onyx is standard ($$). Part price depends far more on geometry, tolerance and quantity than on raw stock — upload a CAD file for a live quote.
Which is easier to machine, Onyx or Slate?
Onyx, by a small margin. Both rate good for machinability — 65/100 against 55/100 for Slate.
Ready to make it?
Upload a CAD file and FabDigit prices the part in Onyx and Slate side by side — material, machining time, tolerance and finish in one quote. Certified material data ships with the order on request.
Typical handbook values for the conditions named above, normalised for comparison. Hardness on non-Brinell scales is converted approximately for charting only. Request certified data with your order for design-critical properties.