Black Sabbath guitarist Tony Iommi revealed his thoughts about Ronnie James Dio. He stated in an interview with MI and said:

“When we did [1980’s] ‘Heaven and Hell’ – it was a time when Ozzy had to depart from the band and we had to get somebody else. And then we tried Ronnie. And I never met Ronnie before; actually, I met Ronnie at a party, but that was it.

And when Ronnie went over to the house – because we used to have a house, we all lived together – and God, when he started singing… Bloody hell… I couldn’t believe what was coming out of his little body. That voice was so good.

At that point with Ozz we haven’t done much because we were all stoned and out of it, and he was worse than us. He lost interest in it. So we needed something to happen, otherwise we would have just broken up. We had to have somebody new coming – and it was Ronnie.

As soon as he came in we started working. And I sat down with him and we wrote, he wrote the lyrics and a melody, and I wrote the riffs – it was a great writing team. And of course at that point Geezer had written all the lyrics with Ozz, which is great – Geezer’s great lyricist as well as a great bass player.

I mean, Ozzy’s great, I’m not knocking Ozzy, he’s brilliant at what he does. But Ronnie was a different singer altogether.

We didn’t want another Ozzy clone. We had tapes sent in and one of the guys sounded just like Ozzy. But it wouldn’t have worked doing that. We had to have something that was different. And Ronnie was the one, and he was great.

Click here to entire interview.