| refer as brown coal | 0.72 |
| fly ash | 0.38 |
| high moisture content | 0.60 |
| the lowest energy conte… | 0.56 |
| high suphur content | 0.25 |
| a low-grade coal | 0.43 |
| the lowest rank of coal | 0.41 |
| used to generate electr… | 0.61 |
| mined | 0.56 |
| formed | 0.51 |
| mined in texas | 0.38 |
| ground | 0.25 |
| exposed to the weather | 0.16 |