The major role of the mineral calcium is in building and maintaining bones and teeth. Calcium is also essential for many other body functions related to the blood, nerves and muscles. One large egg provides 28 milligrams (mg) of calcium, 2.6% of the Daily Reference Value (DRV) for calcium, most of which is in the yolk. An eggshell is composed largely of calcium carbonate (about 94%) along with small percentages of magnesium carbonate and calcium phosphate and, in total, contains about 2 grams of calcium.
– See Daily Values, Daily Reference Values (DRVs), Nutrient, Shell