Geezer Butler is working on his autobiography.

The Black Sabbath bassist has revealed he is halfway through his memoir, which he has penned for his grandkids.

Speaking to Cleveland.com, the 71-year-old rocker said: “I started out because when my parents died, I always wished I’d asked them a lot more things than I knew about.

“I don’t really know much about my mum and dad, ’cause they were always just there. So, I started writing a memoir for my grandkids to read, and that’s been fun going through stuff — old times and growing up in Birmingham, and all that. I’m right in the middle of doing that at the moment.”

The tell-all tome will no doubt be filled with tales about Ozzy Osbourne and co's cocaine-fuelled antics.

On the time the 'Paranoid' rockers lived together in Los Angeles in 1972, Geezer recalled: “We used to have bucket loads of cocaine there, and we had this big bowl in the middle of the table, full of cocaine.

“One day Ozzy noticed this button below one of the windows; He kept pressing it, ‘I wonder what this does?’ The next thing, the police turned up - it was a panic button. And there was us with this great big bowl of cocaine in the middle. So, we dumped all the cocaine down the toilet and ran upstairs to get rid of our own stashes. The coppers went ,‘What’s the problem?’ Oh, nothing... ‘OK, see ya...’ And we’d dumped about five grams of cocaine down the bog!"

The band were notorious for their wild live shows and Geezer recently recalled how he was "nearly blinded" when a Black Sabbath fan threw a giant cross on stage.

Speaking of the band's 'Black Sabbath: 50 Years' exhibition in Birmingham two years ago, he shared: "I'll never forget that. I think it was in San Francisco. Somebody threw this massive bloody brass cross at us, about 18 inches.

"It hit me in the eye. Nearly blinded me. But I kept it.

"There's also a painting someone gave us in Russia, with us as Samurai warriors. Gloriously hideous. We look like four versions of Ken Dodd.

"They found the jacket I wore on our 'Vol. 4' album sleeve. And my silver six-inch platform boots, with red crosses up the sides. God knows how I wore them."

Black Sabbath - which was also made up of guitarist Tony Iommi and previously drummer Bill Ward - formed in 1968 and bid farewell with their final gig in their hometown of Birmingham's Genting Arena in 2017.