Walnut (Knotty) – One of the more beautiful and expensive species, walnut is traditionally used for fine gun stocks, furniture and boat building. It is a dense hardwood that is fairly porous. The color varies from a rich, dark brown to black with purple undertones. Because of the way it grows, the heartwood of the walnut tree grows darker than the sapwood on the outer rings. Walnut features attractive blonde sapwood streaks within the darker tones and it generally has a straight grain with occasional waves or curls.