Underground mining (soft rock)

Underground mining (soft rock) refers to a group of underground mining techniques used to extract coal, oil shale, potash and other minerals or geological materials from sedimentary ("soft") rocks. Because deposits in sedimentary rocks are commonly layered and relatively less hard, the mining methods used differ from those used to mine deposits in igneous or metamorphic rocks (see Underground mining (hard rock)). Underground mining techniques also differ greatly from those of surface mining.