Electric smoker

Good Morning, I have a rather odd question that may I may be over thinking. While building a electric smoker, I plan to use lava rock to retain heat, but i can't find any where that tells me why to use lava rock. lava rock runs about a dollar a pound, unless you have a over abundance of it on your land as the technical name for it is Scoria and is used quite often in many different applications. mean while I have cooked on fire rings made of rock for years. Is their a befit to using the commercial lava rock.