50 Pounds Calcium Carbonate Limestone Powder by The Seed Supply - Rock Dust - Great Soil Amendment and Fertilizer with Endless Uses 50 Pounds Calcium Carbonate by The Seed Supply in original manufacturer bag Used in 100s of Industries for Multiple Situations Increases Minerals in Soil Odor & Moisture Absorpent If using as chalk paint powder you should not expect a completely smooth surface without any sanding. As you can see in the photo, there is a slight grittiness to it, but we have really loved it on projects around our home.