Reddit mentions of Grillpro 7 lb. Lava Rock

I see the "ashy" descriptor come up a fair amount with dark beers that use roasted malts in the ingredients, which is most dark beer. Come to think of it, there literally is "ash" in those beers, which is just the burnt or roasted residue left on the malt. Probably "burnt toast" could be used as a synonym of "ash". "Volcanic rock" (or lava rock), in my mind, would be like licking a (cold) lava rock. I might compare it to a milder, more mineral-y, ash flavor. Something like that.