Question

Calculate the density of a rock composed of the four minerals listed below together with their abundances and densities.

| Mineral | Abundance by volume, % | Density, g/cm3 |
| Olivine | 15 | 3.30 |
| Augite | 50 | 3.20 |
| Plagioclase | 25 | 2.68 |
| Magnetite | 10 | 5.18 |

Hint: The total mass of the rock is the sum of the masses of its minerals

Answer 1

density = mass/volume, mass = volume x density

Density of the rock (dR)

dR = 3.30 × 0.15 + 3.20 × 0.50 + 2.68 × 0.25 + 5.18 × 0.10

dR = 3.28 g/cm3