Introduction to the Holy Pit: The Holy Pit is the largest mine in the world, more than 100 meters deep and hundreds of meters long and wide. There are 76 kinds of minerals in the pit, mainly including lithium, beryllium, tantalum, niobium, rubidium, cesium, cobalt, chromium, uranium and other rare elements. It was this pit that helped the country repay one-third of the debt of the former Soviet Union in the 1960s.