Sulphur or sulfur?

It comes as a surprise to many that “sulfur” is not an Americanism. In fact, the -f- spelling (sulfur, sulfide, sulfate, etc.) is the accepted international spelling and was adopted by the International Union of Pure and Applied Chemistry (the international body that governs chemical element names and symbols) over 30 years ago. It has also been adopted by all recognised mineralogical and geological authorities, including the International Mineralogical Association, the Geological Society of Australia, and The Geological Society of London.