After you make the brick you put it in great ovens called kilns. It takes about seven days to the finish bricks. Glass is one of the most useful manufactured items. It is made of sand, limestone and soda ash which is made from salt. They melt them together until it becomes liquid.
Some glass is flattened to make windows.
Other glass is blown to make bowls and other glass items. Gems are minerals that occur in nature. They are highly valued because they are rare, beautiful and strong enough to last in jewelry . Rubies are found in limestone. The limestone is cut away to free the gem.