A good brick earth should be such that it can easily be moulded and dried without cracking and wrapping. A good brick earth should have the following composition. (i) Alumina or clay (20% to 30%) by weight. (ii) Silica or sand (35% to 50%) by weight. (iii)Silit (20% to 30%) by weight. And the total content of clay and Silt shall not be less than 50%. (iv)Remaining ingredients which include: Lime (Cao), Oxide of iron, Magnesia oxide, Magnese, Sodium potash, the soluble materials shall not be more than 2% by weight.