Hello Adam and all, I'm not arguing the fact that micronutrients can be and are derived from granite. What I don't understand is why one would use granite grit in particular for that purpose. I'm thinking of the time frame. Would you not get more soluble micronutrients from using a sand, a green sand, oyster shells, or for that matter even egg shells in a much more reasonable time frame. Just a thought, I'm just trying to understand why granite would be used specifically for it's micronutrient value. How long would it take for my nutrient tester, which measures in ppm, to measure a change in the nutrient level of a glass of water and granite grit? Linda Foulis Okotoks, AB Canada Still puzzled but eager to learn more.