Strontium is a chemical element; it has symbol Sr and atomic number 38. An alkaline earth metal, it is a soft silver-white yellowish metallic element that is highly chemically reactive. The metal forms a dark oxide layer when it is exposed to air.
Strontium exists in nature, but because it is highly chemically reactive, it is only found in more complex minerals like celestine (or celestite), strontianite, and putnisite. Likewise, when it’s used as the active ingredient in drugs and supplements, it must be bonded to another chemical.
Strontium has properties similar to those of its two vertical neighbors in the periodic table, calcium and barium. It is found naturally in the minerals celestite and strontianite.
Strontium is assimilated in the body in the same way as calcium. In the body, strontium is absorbed into the bloodstream and also behaves similarly to calcium, according to the Argonne National Laboratory. Several types of foods are rich in strontium. Milk and dairy products contain strontium.