| Rock group | Metamorphic |
| Metamorphism type | Regional |
| Protolith | It goes like this:
Peat |
Coal in hand sample
Bituminous coal
Allegheny Formation bituminous coal
Coal and pyrite intermingled
Anthracite
Anthracite displaying greasy lustre
Coal in thin section
Stay tuned for explorable images!
Bituminous coal, plane polars
Magnification: 40x Click here for crossed polars: https://youtu.be/t8hNoiBO0ag
Bituminous coal, crossed polars
Magnification: 40x Click here for plane polars: https://youtu.be/FNPce8bR95s