My grandmother used lava rock to "mulch" her beds, and my mother used the extra on one front bed. None of us would ever use it again, for very different reasons.

My grandmother hates moving it around every time she wants to take out a shrub, weed, plant annuals, etc. It literally hurts your hand to scrape against it--like a pumice stone.

My mother hates the color now, and has worked on removing what she has (stealthily adding it to Gma's yard, where it won't be noticed among the rest). She's replacing it with something more natural looking.

I won't use it for all of the above reasons, but also because it doesn't break down and add any nutrients to the soil. I want my mulch to do double-duty!

As far as wood mulch recommendations go, I don't remember my pine nuggets fading very quickly, but I admit I haven't used wood mulch in a while. I normally just use groundcovers and compost in place of wood chips anymore... sorry. :(

Hope that helps a bit...

Once you have put the rock down, it's a pain to remove. Weeds still pop up and the rocks can end up all over the yard. I will never have it again.