//Clay is not crushed bricks either !//
https://www.masterclass.com/articles/types-of-tennis-courts#4-types-of-tennis-courts
"2. Clay tennis courts. Clay courts mainly come in two different forms: The red clay court is a coarse mixture made from brick,..."
Assuming they don't play on whole bricks, I'm assuming the red powder they quaintly call "clay" consists of crushed bricks. If not please enlighten me. But whatever it is, I still don't like watching tennis played on it.