Wikijunior:The Elements/Calcium Wikibooks, open books ...
Sep 05, 2019· Many rocks such as limestone, marble, chalk, and calcite contain this substance. Limestone caves are a great example of where calcium can be found. Seashells and snail shells are primarily of calcium carbonate. Eggshells are mostly made from this compound too. Calcium is also found in significant amounts in many foods.