It's a native sandstone found throughout the southwest and it goes by a multitude of names. Santa Barbara sandstone is one moniker, Klondike yellow is another. The best approach is to visit a stone yard and pick the material from what they have in stock that fits the application. As a natural material, the color and figure can vary widely and you can be sorely disappointed by just specifying a natural material without seeing it in person. Best of luck!

Thanks for the info and it looks great! Congrats on a wonderful project. The stacked stone reminds us a lot of ours. Especially our Rock Panel products- https://www.norstoneusa.com/products/