| Webster's Online Dictionary |
| Expressions | Domain | Definition | |
| Economic coal reserves | Mining | The reserves in coal seams that are believed to be workable with regard to thickness and depth. In most cases, a maximum depth of about 4,000 ft (1.2 km) is taken, and a minimum thickness of about 2 ft (0.6 m). The minimum economic thickness varies according to quality and workability. See also: thin seam. (references) | |
Source: compiled by the editor from various references; see credits. | Top | ||
