Earth Analogues for Martian "soil"
I just had the weirdest experience - I was vacuming ash from the base of a coal burning fireplace and what appeared to be a big "woolly" clump blocked most of the crevice tool. When I went to clear it I got one of the strongest static shocks I have ever experienced and the clump fell apart revealing a few larger pieces inside. This clump of ash was mostly of a size so small that in the air I would call it smoke. I now know first hand that very dry, extremly small particles can behave in a "clumpy" fashion, and can better understand the strange behavior of the Martian surface.