Your quote: Only the root system of a plant can convert inorganic (rock) minerals into organic minerals.
Answer: Again I will agree with this idea that a plant has this ability to preform in it's system of Life!
But, as usual there may be exceptions to the normal rule of thumb ?
And in this case Life like Bacteria may convert inorganic (rock) minerals into Organic Minerals !
Also the Chemical reaction of an Acid upon the Alkaline Minerals and the presents of a Carbohydrate like Blackstrap Molasses may allow for an Organic Mineral to be formed out of an Inorganic Mineral !
Sorry to Bust your Bubble, but it may not be wise to make such Blanket statements as you are attempting to make !