Rock Density Calculator
Density Tells You What a Rock Is Before You Even Cut Into It
Two rock specimens can look almost identical in a field bag — similar color, similar grain — and still be different materials entirely once you weigh them and measure their volume. Density is one of the fastest, most reliable field checks a geologist has, because it doesn't require a lab, a thin section, or a hand lens: just a mass, a volume, and a division.
The Formula
The result is expressed in grams per cubic centimeter (g/cm³), the standard unit for rock and mineral density in geology. Water displacement is the usual way to measure the volume of an irregular sample: submerge it, record how much water it displaces, and that displaced volume is the rock's volume.
Where Density Measurements Matter
- Rock and mineral identification — density is one of several diagnostic properties (alongside hardness, streak, and luster) used to narrow down an unknown specimen in the field or lab.
- Ore grade estimation — denser samples from a given rock type often indicate a higher concentration of heavy minerals, a quick first-pass signal before assay results come back.
- Geophysical surveying — gravity surveys and seismic velocity models both depend on accurate subsurface density estimates to interpret what lies beneath the surface.
- Construction and quarrying — density feeds directly into calculating the weight of extracted material, which affects transport, blasting, and load-bearing calculations on site.
Typical Density Ranges by Rock Type
| Rock Type | Typical Density (g/cm³) |
|---|---|
| Pumice | 0.25 – 0.9 |
| Sandstone | 2.2 – 2.8 |
| Limestone | 2.3 – 2.7 |
| Granite | 2.6 – 2.7 |
| Marble | 2.6 – 2.8 |
| Gneiss | 2.7 – 3.0 |
| Basalt | 2.8 – 3.0 |
Ranges are typical published values; individual specimens vary with mineral composition, weathering, and pore space.
How to Use This Calculator
- Enter the specimen's Mass (g).
- Enter its Volume (cm³), measured directly or by water displacement.
- Select Calculate to get the density in g/cm³, with the formula applied to your numbers.
Related Calculations
Work out volume first with the Rock Volume Calculator, or narrow down a mineral ID with the Mineral Hardness Calculator.