What kind of clay do the use to put on the feet of the horses to practice racing?

The clay used on the feet of horses for racing practice is typically a type of clay called "kaolin" or "china clay." This clay is chosen for its ability to retain moisture, which helps to keep the horses' hooves cool and reduces the risk of injury. Additionally, it can aid in soothing minor abrasions and injuries. Trainers often mix it with water to create a paste that is applied to the hooves.