An excavation made for obtaining minerals from the bowels of the earth, and the minerals themselves are known by the name of mine. 2. Mines are therefore considered as open and not open. An open mine is one at which work has been done, and a part of the materials taken out. When land is let on which there is an open mine, the tenant may, unless restricted by his lease, work the mine; 1 Cru. Dig. 132; 5 Co. R. 12; 1 Chit. Pr. 184, 5; and he may open new pit’s or shafts for working the old vein, for otherwise the working of the same mine might be impracticable. 2 P. Wms. 388; 3 Tho. Co. Litt. 237; 10 Pick. R. 460. A mine not opened, cannot be opened by a tenant for years unless authorized, nor even by a tenant for life, without being guilty of waste. 5 Co. 12. 3. Unless expressly excepted, mines would be included in the conveyance of land, without being expressly named, and so vice versa, by a grant of a mine, the land itself, the surface above the mine, if livery be made, will pass.