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Calcium is dull gray, but it is shiny when scratched. Other physical properties. Calcium is an excellent conductor of electricity. It is very soft and easily scratched. Chemical properties. Calcium reacts rapidly with air to form a coating of gray oxide, and it burns with a red flame.
We've all heard that calcium is one of the most important nutritional building blocks in our body: The mineral (the most abundant of all in the human body) helps to maintain strong, healthy bones and teeth, and also aids in vascular contraction and muscle function, among other essential functions, according to the NIH.