Grand Canyon Onyx is an inviting blend of gold, tan, red, brown and amber tones with white marble veins, with sporadic jade green formations. As the crown jewel of the marble family, Grand Canyon Onyx is formed as a mixture of clay, carbonates and other minerals which have been transformed under intense pressure and heat deep inside the earth. It takes about 1 million years to create a foot of the stone. Grand Canyon Onyx Large Landscape Boulders make an excellent focal point for your landscape design. With their timeless appeal, these boulders will enhance any natural setting and add a mature look to your outdoor concept. Boulders are washed, palletized, and banded.