The more compact grained and heavier a stone the harder it is. Due to alternate wetting and drying the resulting crushing strength can be reduced even up to 3040%. Being dry stones allow more crushing strength than when wet. It is the ability of a stone to endure and maintain its essential and distinctive characteristics resistance to decay, strength and
Oct 17, 2019· Surface mining is a method of mining used to extract minerals and metals which are near the surface of the Earth. There are three basic types of surface mining: open pit mining, strip mining, and quarry methods are much more economical than underground mining, yet they can have a more significant impact on the surrounding environment unless efforts are taken to reclaim the land.