A quality eggshell contains about 2.2 grams of calcium carbonate, the compound that gives them their strength. Eggshells also contain lesser amounts of magnesium, phosphorus, iron, copper, and ...

Add Yahoo as a preferred source to see more of our stories on Google. Gardener with basket of egg shells spreading crushed shells around tomato plant - VH-studio/Shutterstock A quality eggshell ...