Colorado Blue Spruce grows in the same forests as Englemann here in Colorado. It is typically little stiffer than Engelmann and the grain shows more seasonal variability. It is a beautiful white wood that is stiff and light, ideal features for a soundboard wood. I use it a lot and some builders have used it in some very expensive guitars. Not a well-known wood, but one of my favorites, very similar in tone characteristics to Engelmann. Occasionally this wood has a pronounced "curl" or wave and is quite distinctive.