Heartwood is white to reddish brown, with pale sapwood that isn’t clearly distinguished from the heartwood. Color tends to darken with age.
Fir is a favorite Christmas tree species, and its resin is used to make Canada balsam. Such resin (when purified) has very good optical qualities, and was used as an adhesive in bonding optical elements and lenses up until the 1940s, when it was replaced by synthetic resins.
Fir is divided into different groupings, with the primary species in the western United States belonging to the white fir group, while Balsam Fir being the sole commercial species in eastern North America.