Degasification is classified as pre-drainage or post-drainage, depending on whether it is done before or after this process. This process is the primary application of a failure criterion relating major and minor principal stresses called the Hoek-Brown criterion. A form of breast stoping called the room and pillar method is commonly used in this process. Oxidation of sulfides by Acidithiobacillus bacteria can cause an (*) "acid drainage" named for locations (10[1])for this process. (10[1])Desired materials obtained through this process typically must then undergo froth (10[1])flotation (10[1])to remove (10[1])gangue. (-5[1])Mountaintop (10[1])removal (10[1])is an (10[1])approach (10[1])to this process (10[3]-5[1])in which (10[1])explosives are (10[1])used (10[1])to (10[1])remove overburden, (10[1])thus exposing underlying seams. (10[1])For 10 points, name this process in which economically valuable ore (10[4])is extracted from (10[1])underground. (10[2])■END■