A chemical element, symbol Rf, atomic number 104. Rutherfordium is the first element beyond the actinide series, and the twelfth transuranium element. In 1964 G. N. Flerov and coworkers at the Dubna Laboratories in the Soviet Union claimed the first identification of rutherfordium (element 104). A. Ghiorso and coworkers made a definitive identification at the University of California, Berkeley, in 1969 and suggested the name rutherfordium (symbol Rf).