Dragon gives birth to nine sons, why can a kind of soil burn blue bricks and red bricks?

There is a difference between blue bricks and red bricks when they are cooled: red bricks are naturally cooled and blue bricks are cooled with water.

The blue brick is mainly ferrous oxide, and the red brick is iron oxide. Both red bricks and blue bricks are made of clay, but they are made in different ways. Why can the same brick be burned into red brick and blue brick?

You can do a small experiment: take a small piece of green tile and put it between the first coal cake and the second coal cake in the coal cake furnace (counting down from the mouth of the furnace). After about 30 minutes, take out the broken tiles and you will see that the green tiles have turned into red tiles. If you put this red tile on the first coal cake for another 30 minutes, it will turn into a green tile again. Yes