**Acknowledgements**

This work has been initially funded by the Regione Toscana (Italy) by means of the LAMMA Consortium in the framework of the project of a volcanological monograph of Monte Amiata edited at the end of 2017, and then by JRC-EPOS project. Prof. Luigi Marini is acknowledged for the fruitful discussion on fluid fraction inside Monte Amiata magmas. SLF is grateful to T. Abebe Adhana for priceless help in optical microscope observations.
