Strontium Strontium Strontium is the chemical element with symbol Sr and atomic number 38. An alkaline earth metal, strontium 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 has physical and chemical properties similar to those of its two vertical neighbors in the periodic table, calcium and barium. It occurs naturally mainly in the minerals celestine and strontianite, and is mostly mined from these. While natural strontium is stable, the synthetic Sr isotope is radioactive and is one of the most dangerous components of
Tibetan silver iron 'cheese metal' casting, overlaid with this pewter and silver plating. Dependent on source, these can be either thick and robust, or attractive but easily broken due to a loose, fragile inner casting. The latter productions are therefore only suitable for small castings up to around 12 mm, or transient 'fashion' jewelry with a short lifespan. Tibetan silver Tibetan silver is used primarily in jewelry components, and is similar to pewter – an alloy of copper, and sometimes tin or nickel, with a small percentage of pure silver. Its overall appearance is of aged silver, but it can be polished