What type of rock is the Great Wall of China made out of?

This ancient great wall was actually built of wood, earth, grass, and three principal different types of stone: granite (magmatic rock), white marble (metamorphic rock) and and white stones (sedimentary rock, like sandstone and limestone). The stone(s) are from the hills surrounding the area, therefore many types of stones are involved in the construction including a white metorite. The answer is vast and to name a single stone would be incorrect. See the geology of that area. This was a massive undertaking and needed thousands of workers. Over 300,000 workmen, criminals and political prisoners were dragged off to build the wall. Many died from starvation, fighting, or just plain exhaustion before even getting to the construction sites. It is thought that some of the dead were buried in the foundations of the wall to ward off evil spirits. For the surviving workers, the problem they faced was the constantly changing terrain as they travelled west. There wasn't always rock available, so they used earth and rubble that they pounded until it was hard. In other places the hills were so steep that oxen couldn't pull the carts of rock up to the building site, so the men themselves carried the rocks on their backs. In the desert, the wall was built using sand, pebbles and grass. Shi Huang Di became the first emperor of a united China and decided that the various walls needed to be fortified and joined together. He ordered thousands of watchtowers to be built 12 metres tall and 12 square metres at their base with 6-metre walls of granite joining them