Interesting facts about calcium

People have used calcium's compound in cement. Calcium was not discovered until electricity was available for use in experiments. It was first isolated by sir Humphrey Davy in 1808 in London. Stalactites are mainly calcium carbonate. Pure calcium is actually metal, and reacts very strongly, sometimes violently (explosively) with and acids.

Calcium carbonate is a white, insoluble solid occurring naturally as chalk, limestone, marble, and calcite, and forming mollusk shells and stony corals.