Juglans Cinerea. Butternut, also known as white walnut, has a straight grain that can be wavy or curly, giving it a beautiful, unique appearance. The heartwood color of butternut ranges from light to medium brown, and it often has darker streaks. Butternut has a low to medium density, with an average of 420 kg/m3, making it relatively lightweight and easy to work with. Invest in the beauty and durability of natural wood with our exquisite slab supply.