By "MARBLE" I assume you mean the material that statues are carved from and not those cat-eyed round glass balls that little boys play with. The mineral known as "MARBLE" is in fact limestone, calcium carbonate, or just plain old oyster shell. Mineral marble has undergone a long and intense period of heat and pressure while buried underground. There use to be a brand of chicken grit known as "Marble Grit" that also served as a substitute for oyster shell. So yes mineral marble is fine for chickens but I question what is meant by "DUST"...On our bags it just lists calcium carbonate and I do not know if Marble powder is the form of it or not since it is not listed as Marble Powder.