Does anyone know if you can mill soapstone and if the life of the tool is better / worse than say alum. Is it abrasive and any other health issues? Do you need coolant? On the Mohr / Mohs scale talk (soapstone) is the softest mineral (softer than finger nail). Also would limestone be similar to machine, cant find a reference to its Mohs hardness or are there other minerals that are easy to machine?