*** 1/2 MIDNIGHT OIL “Blue Sky Mining” <i> Columbia</i>

Oil . . . slick?

Not exactly. But “Blue Sky Mining” is the Australian punk-alumnus outfit’s least outrightly aggressive album to date, with most tracks settling into a seething, mannered mid-tempo. The Hollywood Palladium pit-kids who gather for Midnight Oil’s tri-annual visits will have a hard time moshing too much to this one.

In actuality, the Oilers have produced an album with as much rage as anything this side of an N.W.A record--probably more, of the genuine sort--but it’s suppressed under a mineral-rich wellspring of pop instincts in which slash ‘n’ burn ‘n’ croak figures less and less.

Not that it’s easy. The structure of the opening salvo, “Blue Sky Mine,” is almost impossible to follow the first time through. You’ve heard what seems to be the chorus twice when the song kicks into an altogether different, second chorus: So which one is the hook? It’s the kind of joyful, wonderful hit (to soothsay a bit) that you love--that has a shelf life--precisely because it does take a few listens to get.

Some of the other songs an American could listen to all year and still not comprehend--lyrically, Oil dares to be provincial. Last album, it was aboriginal land rights; this year, it’s the rape of the environment that dominates singer/politico Peter Garrett’s concerns. Seems that Down Under there are a lot of mountains with great, gaping, ugly holes left in them (by those who “strangled and wrestled the ground / But they never put anything back,” aided by “a government with axes in its eyes”), and other stuff Qantas left on the cutting room floor.

Despite all the anger, the apocalyptic strain of “Red Sails in the Sunset” (still the band’s masterpiece) has been usurped by a messianic one here, which may help explain some of the musical evolution as well. Color Garrett a hopeful crank who--in insisting on recycled album packaging, among other things--puts his money where his very big mouth is.