Starting when you select this feat, your ability to alter the physicial properties of one non-magical object, changing it from one substance into another, is enhanced.
Your minor alchemy gets faster, you can now transform one object (up to 1 cubic foot) composed entirely of wood, stone (but not a gemstone), iron, copper, or silver into a different one of those materials instantaneously. For each 3 minutes you spend performing the procedure, you can transform up to 1 cubic foot more of material. After 1 hour, or until you lose your concentration (as if you were concentrating on a spell), the material reverts to its original substance.
Complex transmutation:
You can also now try transforming these objects into different materials that are not listed in the text above such as: clay, sand, wax, glass, and so on. (Up to the DM's discretion).
Doing this transformations takes 6 minutes for each cubic foot of material you transmutate.
You must make an Intelligence (Arcana) check against a DC set by the DM. (Keep in mind that the DM must set the DC based on things such as: The quantity being transmutated, the complexity of the material being transmutated to, and other factors that may alter or complicate/ease the process.)
If the check is failed you must perform a Long Rest before attempting another Complex Transmutation.