Inorganic and Organic Matter in Eggshell

Correct Answer: 96% & 4%

Eggshell is composed of 96% inorganic matter and 4% organic matter.

Eggshell Composition Breakdown

• Inorganic matter (96%):
  • Calcium carbonate (CaCO₃): 94%
  • Magnesium carbonate (MgCO₃): 1%
  • Calcium phosphate (CaHPO₄): 1%
• Organic matter (4%): Mainly protein matrix (osteopontin, ovocleidin)

This high inorganic content makes eggshell essentially a calcium carbonate crystal structure, which is why calcium deficiency directly results in soft or thin-shelled eggs. Shell strength is directly proportional to shell thickness (measured by screw gauge).