Experiment of Calcium Carbonate Composition of Eggshells
Approximately 94% of a dry eggshell is calcium carbonate and has a typical mass of grams,1 although these values can differ depending on sources. Amounts as low as 78% have been published. The remaining mass is composed largely of phosphorus and magnesium, and trace amounts of sodium, potassium, zinc, manganese, iron, and copper.