Metalloid silicon, germanium, arsenic, antimony, and tellurium are commonly recognised as metalloids. Depending on the author, one or more from selenium, polonium, or astatine are sometimes added to the list. Boron sometimes is excluded, by itself, or with silicon. Sometimes tellurium is not regarded as a metalloid. The inclusion of antimony, polonium, and astatine as metalloids has been questioned. Other elements are occasionally classified as metalloids. These elements include hydrogen, beryllium, nitrogen, phosphorus, sulfur, zinc, gallium, tin, iodine, lead, bismuth, and radon. The term metalloid has also been used for elements that exhibit metallic lustre and electrical conductivity, and that are
Antimony risk index. This indicates that it has currently the second highest supply risk for chemical elements or element groups which are of economic value to the British economy and lifestyle. Furthermore, antimony was identified as one of 20 critical raw materials for the EU in a report published in 2014 (which revised the initial report published in 2011). As seen in Figure xxx antimony maintains high supply risk relative to its economic importance. 92% of the antimony is imported from China, which is a significantly high concentration of production. Much analysis has been conducted in the U.S. toward defining which