Friction of anodized aluminum

Does anybody know what the relative coefficients of friction are for:

aluminum on aluminum
(regular) anodized aluminum on (regular) anodized aluminum
hard-anodized aluminum on hard-anodized aluminum.

Is there much difference? How important is the surface finish of the rubbing parts vs. the anodizing?

We have some aluminum parts that need to slide on each other, and we are planning on possibly anodizing (a) to decrease wear and (b) to decrease friction. Obviously going to hard anodizing will be the best for decreasing wear, but I was also wondering about friction effects.

I can not give you actual values, but aluminum on aluminum would be a bad choice. It will gall. Anodize is better. Anodize with a teflon dispersion (really a top coat of teflon particles in something like a silica matrix-Is too big to actually enter the pores of the anodize, even tho vendors will try to give that impression) is much better and hard anodize is the best of the choices that you gave. Any lubrication possible, even water will make it last longer.