The gravel that expelled out my feet, and calves, was real small and off white, probably about 1/16th of an inch. I first noticed them when I started expelling toxics out the web of two of my fingers one night. The toxics were mercury colored, and had a mercury like appearance. I was washing my hands, and they just went flying out, then I heard the gravel hitting the sink. Allergies like poison oak, and pollens, expel out the hand areas also blistering first.