These are quartz crystals and feldspar, so most sand in the world on the mainland is made of quartz crystal and feldspar. It's the erosion of granite rock.
这些是石英晶体和长石 也就是说地球大陆上大多数的沙 都是石英晶体和长石构成的 是花岗岩被侵蚀后的产物