Density of Basalt: Porosity, Velocity and Strength Values
The density of basalt typically runs from 2.8 to 3 g/cm3, or about 2800 to 3000 kg/m3, with porosity of 0.1 to 1 percent. Compressional seismic velocity sits near 5.5 to 6.5 km/s and unconfined compressive strength spans 100 to 300 MPa. The table below collects the values; the notes explain why the ranges are as wide as they are.
| Property | Typical range |
|---|---|
| Density | 2.8 to 3 g/cm3 |
| Porosity | 0.1 to 1 percent |
| P wave velocity | 5.5 to 6.5 km/s |
| Unconfined compressive strength | 100 to 300 MPa |
| Mass of 1 m3 (mid density) | about 2.90 tonnes |
Why the range
The densest common volcanic rock. Vesicular flow tops can drop density and strength dramatically, which is why basalt aggregate is tested lot by lot. For design work, treat these as screening values: a specific site deserves specific testing, and the calculators linked below show how each number is measured and used.
Use these values
- Rock Density Calculator to build density from mineral composition.
- Porosity Calculator to measure porosity from well logs.
- The Property Library for every rock, soil, and mineral on this site.
Related Calculators and Reference
- Rock Density and Specific Gravity Calculator, for the conversion when your source quotes specific gravity and your spreadsheet wants density.
- Two Way Time to Depth Converter, since these velocity ranges feed straight into time to depth work.
- Density of Granite, for the comparison that decides which unit you are actually looking at.
- Density of Conglomerate, for the lithology most often logged next to it.
- USGS Mineral Resources Program, published rock and mineral property data.