Poor Black Sabbath had really fallen on hard times after the departure of Ronnie James Dio.

He might have been the last truly respected singer in their history, and even his efforts couldn't win over the Ozzy Osbourne fans who had jumped ship and started following Osbourne's solo career.

So The Sabbath Stones tries to detail the period between Dio's initial run with the group and their reunion with Osbourne in 1997.

What this leaves for source material is one underrated but bland album with Ian Gillan and the original rhythm section, one mind-numbing disaster with Glenn Hughes on the mic, one reunion album with Dio, and four bizarre power metal experiments with singer Tony Martin.

Most of the material is taken from Martin's years with the group, and surprisingly enough there are some good songs featuring him.

Although they are light years from "Hole in the Sky," guitarist/original member Tony Iommi managed to write some catchy anthems with Martin.

"Headless Cross," "The Shining," and "Virtual Death" are standouts from their collaborations, running the gamut between stoner rock and power metal.

Too much material is taken from Tyr, their weird Viking/Norse mythology concept album that fell flat for fans and critics alike.

They also include a minute-long keyboard instrumental from the same album that needlessly takes up space between songs.

The motivation is that IRS Records owned the rights to only a few of the albums, hence they over-emphasize the albums that they do own.

But this does the band a great disservice, leading listeners to think their entire post-Dio period was made up of high-concept power metal.

"TV Crimes," the lone track from the awkward Dio reunion of 1992, sounds like the same preachy Dungeons and Dragons rock he was making on his own, but with much better guitar playing.

The material from Forbidden, their last album with Martin, is probably the worst of the bunch.

These songs are confused, produced badly, and virtually unrecognizable when compared to the first 15 years of their career.

As far as the pre-Martin material goes, the Ian Gillan-sung "Disturbing the Priest" is decent but they should have gotten "Zero the Hero" if they were to utilize that album.

And "Heart Like a Wheel" from Iommi's experimental Seventh Star is so incredibly bad, yet it might be the best choice from that album anyway.

This is obviously a mixed bag, but strangely it works if only for the history lesson it provides.

Fans of classic Sabbath should be given extreme caution -- this music is very different from anything they did with Ozzy Osbourne.

Instead, this is the sound of an excellent band handling their fall from grace about as ungracefully as they could, and the entertainment value in that alone is worth the purchase.