Is granite better than other surface plate materials like cast iron or glass? Why? Yes, granite is a far superior material for a surface plate than its comparators cast iron, glass, or metal. Granite comes with a number of advantages that overall allow your surface plate to last longer and to provide more reliable measurements. Granite does not rust or corrode overtime and it is almost impossible for granite to warp. Only under rare and extreme environmental circumstances would granite suffer the same damage that cast iron, glass, or metal might. When granite does get nicked or chipped, there is no compensatory hump. Granite has a longer wear life, a greater degree of precision, smoother overall action, a low maintenance cost, and a low coefficient of thermal expansion. Finally, there is no magnetic quality to granite with makes granite surface plates safer in the presence of multiple other materials.