Slabs for Sale › Black Walnut Slab - Stock 23AB Image 1 of 1 Black Walnut Slab - Stock 23AB $210.00 sold out This 9/4 thick black walnut slab is 71” long. It varies in width from 19-20.5”. Sold Out Added! This 9/4 thick black walnut slab is 71” long. It varies in width from 19-20.5”.