Fulgurate 1 : A glass-like structure that forms around the element of a current limiting fuse when it operates. It is causes when the heat of the arc melts the silica sand surrounding it
Young & Company Electric Power Products and Related Engineering Services, Glossary of Electrical Terms, http://www.youngco.com/young2.asp?ID=4&Type=3, CA., USA 2001. (Electr Sfty - Amer) {514}