Table 13. Generalized chemical composition of common rock types reported on an oxide basis(*). Differing rock types have very different concentrations of essential plant nutrients.
| Element | Granite/Rhyolite | Andesite/Dacite | Gabbro/Basalt | Sandstone | Shale | Limestone |
|---|
| SiO2 | 72.08 | 59.01 | 48.36 | 78.33 | 58.10 | 5.19 |
|---|
| TiO2 | 0.37 | 1.05 | 1.32 | 0.25 | 0.65 | 0.06 |
|---|
| Al2O3 | 13.86 | 15.98 | 16.84 | 4.77 | 15.40 | 0.81 |
|---|
| Fe2O3 | 0.86 | 2.05 | 2.55 | 1.07 | 4.02 | 0.54 |
|---|
| FeO | 1.67 | 5.20 | 7.92 | 0.30 | 2.45 | -- |
|---|
| MnO | 0.06 | 0.13 | 0.18 | trace | trace | trace |
|---|
| MgO | 0.52 | 4.03 | 8.06 | 1.16 | 2.44 | 7.89 |
|---|
| CaO | 1.33 | 6.53 | 11.07 | 5.50 | 3.11 | 42.57 |
|---|
| Na2O | 3.08 | 3.63 | 2.26 | 0.45 | 1.30 | 0.05 |
|---|
| K2O | 5.46 | 1.38 | 0.56 | 1.31 | 3.24 | 0.33 |
|---|
| P2O5 | 0.18 | 0.28 | 0.24 | 0.08 | 0.17 | 0.04 |
|---|
| CO2 | -- | -- | -- | 5.03 | 3.43 | 51.54 |
|---|
| SO3 | -- | -- | -- | 0.07 | 0.64 | 0.05 |
|---|
| H2O | 0.53 | 0.75 | 0.64 | 1.63 | 5.00 | 0.77 |
|---|
| Total | 100.00 | 100.00 | 100.00 | 99.95 | 99.95 | 99.84 |
|---|
(*) Data for igneous rocks after Nockolds (1954); data for sedimentary rocks from F.W.Clarke (1924).