50 years ago today (8/4/75), then ex-Deep Purple guitarist Ritchie Blackmore released his first album as leader of Ritchie Blackmore’s Rainbow. This self-titled release featured members of proto-hard rockers Elf and a fiery young singer, Ronnie James Dio. The album was ahead of its time, featuring fantasy lyrics and a then-innovative approach to metal that was prog and thunderous. Watch Rainbow perform the heralded “Man on the Silver Mountain” live for the first time in 1977…