· Coal Authority 1994 to date. 4. Records before 1850. Many mines and quarries were on land owned by the Crown, the Duchy of Lancaster or the Duchy of Cornwall. The National Archives holds records of these as well as some privately owned mines and quarries. Search our alogue using keywords such as 'mine' and/or 'mining'.
· Machine size—The excavator size you'll need will depend on the weight of the materials you'll be lifting. A mini (or compact) excavator can handle up to six metric tons (or 13,227 pounds). A midsized excavator handles 610 metric tons (or 22,046 pounds) and the standard (or fullsize) excavator is equipped to lift up to 10 90 metric tons (or 22,046 198,416 pounds).