Motley Crue star Nikki Sixx is in mourning following the death of his mother.

Deana Richards passed away of unknown causes on Saturday (08Jun13) at the age of 74.

The bassist, who was primarily raised by his mum after his father Frank Serafino abandoned the family, announced the sad news on, writing, "RIP Mom 5-5 1939 to 6-8 2013".

The rocker has yet to break his silence on the loss, but in a cryptic post on he appeared to make a reference to his formerly strained relationship with his mother, who also ended up leaving Sixx at a young age, forcing him to live with his grandparents.

It says, "Writing a beautiful song about regret.....Pain always serves up the most brutal truth. I cannot see a ray of sunshine and not find the beauty in the inevitable rain cloud coming in behind it...I have made mistakes....Do lyrics and melody really make up for lost time?

The Saying 'this Too Shall Pass' Works Both Ways."