Volcanic rock, any nutrients?
I hear about adding Azomite and other rock dusts to soil. PLEASE keep your responses simple and to the point. Those black and red colored "pumicy" rocks you can get for mulch at the big box stores, are they rich in anything besides just pumice? Is there any iron, potassium, magnesium, phosphorous, calcium or trace minerals be they good or bad like too much aluminum? There was a post a while ago about volcanic soil in a part of Italy and these WONDERFUL tomatoes grown there. I know I should test my soil before adding much more than OM, but I wonder if this stuff has any mineral content use, or is just bonsai soil additive and mulch? Don't get too scientific until after you give me the answer for dummies. I realize the answer isn't always that simple, but try to give me the simplest answer before all you get into the long version. Thank you all who answer.