2 Lb Calcium Carbonate Limestone Powder by The Seed Supply - Rock Dust - Great Soil Amendment and Fertilizer 2 pounds of Calcium Carbonate by The Seed Supply 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.