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
Element Six oil and gas drilling to precision machining and electronics. Products offered by Element Six fall into two broad categories - superabrasives and advanced diamond products. The largest part of the company's business today is in superabrasives. These products are based on the world's hardest materials such as synthetic diamond and cubic boron nitride that are used in a wide range of cutting, grinding and drilling applications range from oil and gas exploration to machine tools, automotive part manufacturing and marble production. Element Six Element Six is a member of the De Beers Group of Companies, its majority shareholder. Element Six