Why did the terracotta army become stone or why is it stone?

Question

its for a project am doing at school

Answer 1

they were made out of stone (clay) to begin with. i dont belive they turned into stone

Answer 2

Terra cotta is a hard, fired clay, brownish-red in color when unglazed, that is used for architectural ornaments and facings, structural units, pottery, and as a material for sculpture. Terra cotta is a type of clay not stone.

Answer 3

I don't know about them turning to stone. They are suffering from a growth of mold, and there is some oxidation which is turning them grey.

The reason for the mold is the humidity of the environment that they are housed in and, oddly enough, from the breath of the tourist who come to see them.

The oxidation is caused by their exposure ot the air. Some in China deny this and say that the grey color is caused by the soot of coal burning plants in the surrounding area.