How does a brick made of BLACK clay turn into RED?
anyway what reactions take place in a brick kiln?
Answer:
Over the period of firing, brickclay becomes a metamorphic rock. Clay minerals break down, release chemically bound water, and change into a mixture of two minerals, quartz and mullite. The quartz crystallizes very little in that time, remaining in a glassy state.
The key mineral is mullite (3AlO3 · 2SiO2), a blended compound of silica and alumina that is quite rare in nature. It is named for its occurrence on the Isle of Mull in Scotland. Not only is mullite hard and tough, but it also grows in long, thin crystals that function like the straw in adobe, binding the mix in an interlocking grip.
Iron is a lesser ingredient that oxidizes into hematite, accounting for the red color of most bricks. Other elements including sodium, calcium and potassium help the silica melt more easily—that is, they act as a flux. All of these are natural parts of many clay minerals.
It is a chemical reaction that takes place because of the heat in the kiln, and the reactants in the brick. I have seen it, sorry that I do not have the equations.
Black clay having magnesium and so many elements. When bricks are made.The black clay mixed with SAND,having silicon.When it burns magnesium react with oxygen and make magnesium oxide and silicon turns into silicate.both is red . so black clay turns into red.
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