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Granite vs Slate

Natural Material · grade comparison

Granite and Slate are both natural material grades. Slate is the stronger of the two: tensile strength 16 MPa (2.32 ksi) against 12 MPa (1.74 ksi) for Granite, about 33% more. Granite is lighter (2.68 g/cm³ vs 2.8 g/cm³ for Slate) and Slate is stiffer (65 GPa vs 50 GPa). On the shop floor, Slate machines more easily (good vs poor).

GraniteChoose it when weight is the constraint.

SlateChoose it when strength drives the design, or when the part sees heat.

Granite vs Slate: properties

GraniteSlate

Mechanical

Strength, stiffness, ductility and hardness at room temperature.

Elastic (Young's) Modulus

50 GPa7.3 Msi
65 GPa9.4 Msi

Shear Modulus

21 GPa3 Msi
25 GPa3.6 Msi

Tensile Strength (Ultimate)

12 MPa1.7 ksi
16 MPa2.3 ksi

Compressive Strength

180 MPa26.1 ksi
190 MPa27.6 ksi

Flexural Strength

14 MPa2 ksi
75 MPa10.9 ksi

Shear Strength

20 MPa2.9 ksi
22 MPa3.2 ksi

Fracture Toughness (K_IC)

1.2 MPa·√m1.1 ksi·√in
1.1 MPa·√m1 ksi·√in

Hardness, Knoop

650 HK
400 HK

Hardness, Mohs

6.5
4

Same in both: Bulk Modulus 40 GPa5.8 Msi · Poisson's Ratio 0.22 · Elongation at Break 0.05%

Physical

Density and transition temperatures.

Density

2.68 g/cm³0.1 lb/in³
2.8 g/cm³0.1 lb/in³

Melting Point (Solidus)

1,215°C2,219 °F
—

Porosity

0.7%
0.5%

Thermal

How each material carries heat and how hot it can run.

Thermal Conductivity

2.9 W/m·K1.7 BTU/hr·ft·°F
2.1 W/m·K1.2 BTU/hr·ft·°F

Specific Heat Capacity

800 J/kg·K0.19 BTU/lb·°F
760 J/kg·K0.18 BTU/lb·°F

Thermal Expansion (CTE, 20–100 °C)

8 µm/m·K4.4 µin/in·°F
9 µm/m·K5 µin/in·°F

Max Service Temperature (continuous)

300°C572 °F
450°C842 °F

Min Service Temperature

-60°C-76 °F
-50°C-58 °F

Electrical

Conductivity and insulation.

Electrical Resistivity

10,000 Ω·m3.94×10¹¹ µΩ·in
1,200,000 Ω·m4.72×10¹³ µΩ·in

Dielectric Strength

—
1.5 kV/mm38.1 V/mil

Chemical & Environmental

Corrosion and environmental resistance (0–100 scores).

Corrosion Resistance

88 / 100
86 / 100

Manufacturability

FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.

Machinability

25 / 100
55 / 100

Polishability

85 / 100
38 / 100

Sustainability

Primary-production footprint per kilogram.

Embodied Energy (primary production)

6 MJ/kg2,580 BTU/lb
0.9 MJ/kg387 BTU/lb

Embodied Carbon (primary production)

0.45 kg CO₂/kg
0.06 kg CO₂/kg

Embodied Water

12 L/kg1.4 gal/lb
8 L/kg0.96 gal/lb

Typical Recycled Content

0%
2%

Common Calculations

Ratios derived from the values above.

Specific Strength (UTS / density)

4 kN·m/kg
6 kN·m/kg

Specific Stiffness (E / density)

18.7 MN·m/kg
23.2 MN·m/kg

Thermal Diffusivity

1.4 mm²/s
1 mm²/s

Same in both: 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

CapabilityGraniteSlate
Default condition——
Relative cost$ Budget$ Budget
Min. machined wall——
Best machined surface——

Granite vs Slate — frequently asked

Is Slate stronger than Granite?

Yes. Slate has a typical tensile strength of 16 MPa (2.32 ksi) against 12 MPa (1.74 ksi) for Granite — about 33% more.

Which is cheaper, Granite or Slate?

Both sit in the same relative cost tier ($, budget); the part price will be decided by machining time, tolerance and quantity rather than by the material.

Which is easier to machine, Granite or Slate?

Slate. Its machinability rates good (55/100) against poor (25/100) for Granite.

Ready to make it?

Upload a CAD file and FabDigit prices the part in Granite 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.