Zircore and Kyasill is a naturally occurring rounded grain mineral mined from Chemours heavy mineral deposits in Starke, FL. This foundry sand product is primarily composed of zircon and aluminum silicates. It is washed to give a clean product free from dirt and ultrafines. Two grades of sand are available as Zircore or Kyasill, differentiated by the level of zircon (zirconium silicate) and aluminum silicates. Zircore is typically 50% zircon sand and 34% kyanite + sillimanite, whereas Kyasill generally is 35% zircon sand and 47% kyanite + sillimanite.