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Limestone vs Slate

Natural Material · grade comparison

Limestone and Slate are both natural material grades. Slate is the stronger of the two: tensile strength 16 MPa (2.32 ksi) against 5 MPa (0.725 ksi) for Limestone, about 3.2 times as much. Limestone is lighter (2.4 g/cm³ vs 2.8 g/cm³ for Slate) and Slate is stiffer (65 GPa vs 30 GPa). On the shop floor, Limestone machines more easily (very good vs good).

LimestoneChoose 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.

Limestone vs Slate: properties

LimestoneSlate

Mechanical

Strength, stiffness, ductility and hardness at room temperature.

Elastic (Young's) Modulus

30 GPa4.4 Msi
65 GPa9.4 Msi

Shear Modulus

12 GPa1.7 Msi
25 GPa3.6 Msi

Bulk Modulus

25 GPa3.6 Msi
40 GPa5.8 Msi

Poisson's Ratio

0.25
0.22

Tensile Strength (Ultimate)

5 MPa0.73 ksi
16 MPa2.3 ksi

Compressive Strength

55 MPa8 ksi
190 MPa27.6 ksi

Flexural Strength

7 MPa1 ksi
75 MPa10.9 ksi

Shear Strength

10 MPa1.5 ksi
22 MPa3.2 ksi

Fracture Toughness (K_IC)

0.45 MPa·√m0.41 ksi·√in
1.1 MPa·√m1 ksi·√in

Hardness, Knoop

120 HK
400 HK

Hardness, Mohs

3
4

Same in both: Elongation at Break 0.05%

Physical

Density and transition temperatures.

Density

2.4 g/cm³0.09 lb/in³
2.8 g/cm³0.1 lb/in³

Porosity

12%
0.5%

Thermal

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

Thermal Conductivity

1.7 W/m·K0.98 BTU/hr·ft·°F
2.1 W/m·K1.2 BTU/hr·ft·°F

Specific Heat Capacity

880 J/kg·K0.21 BTU/lb·°F
760 J/kg·K0.18 BTU/lb·°F

Thermal Expansion (CTE, 20–100 °C)

6 µm/m·K3.3 µin/in·°F
9 µm/m·K5 µin/in·°F

Max Service Temperature (continuous)

400°C752 °F
450°C842 °F

Min Service Temperature

-40°C-40 °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

25 / 100
86 / 100

Manufacturability

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

Machinability

80 / 100
55 / 100

Polishability

45 / 100
38 / 100

Sustainability

Primary-production footprint per kilogram.

Embodied Energy (primary production)

1 MJ/kg516 BTU/lb
0.9 MJ/kg387 BTU/lb

Embodied Carbon (primary production)

0.09 kg CO₂/kg
0.06 kg CO₂/kg

Embodied Water

15 L/kg1.8 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)

2 kN·m/kg
6 kN·m/kg

Specific Stiffness (E / density)

12.5 MN·m/kg
23.2 MN·m/kg

Thermal Diffusivity

0.8 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

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

Limestone vs Slate — frequently asked

Is Slate stronger than Limestone?

Yes. Slate has a typical tensile strength of 16 MPa (2.32 ksi) against 5 MPa (0.725 ksi) for Limestone — about 3.2 times as much.

Which is cheaper, Limestone 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, Limestone or Slate?

Limestone. Its machinability rates very good (80/100) against good (55/100) for Slate.

Ready to make it?

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