It's a Billy Joe Shaver song and his excellent album with that as the title track - 'I'm just an old chunk of coal ... but I'm gonna be a diamond some day' - has been reissued on CD: Koch CD-7904. Not as good as his classic 'Old Five and Dimers Like Me' album, but great stuff. The song is also included on another great reissue - Willie N., Waylon J., Kris K. and Billy Joe S. 'Honky Tonk Heroes' Pedernales/Freefalls FFE 7008 2 - 10 Billy Joe Shaver songs done by that motley crew of Outlaws.

--Stewie.