What is Onyx made of? 63% of onyx is a hydrate crystal–Al2O3+3H2O. Alumina is also the main ingredient in Corian and all “solid surface” products. The main ingredient in our product is (alumina trihydrate). Our other 37% is a special polyester resin we developed over the last 30 plus years.
Our resin does not contain any urea-formaldehyde.