_Applied_  
_sciences_  
**Non-Destructive and Micro-Invasive Techniques for Characterizing the Ancient Roman Mosaic Fragments**  
**[PERSON] 1,2,*, [PERSON] 3,4, [PERSON] 3, [PERSON] 3, [PERSON] 3,4,5, [PERSON] 6,7,*, [PERSON] 6, [PERSON] 6, [PERSON] 6, [PERSON] 6, [PERSON] 6, [PERSON] 1,2, [PERSON] 1,2 and [PERSON] 2**  
Doctoral School of Engineering Sciences, Valahiu University of Targoviste, 130105 Targoviste, Romania; [EMAIL_ADDRESS] (L.L.); [PERSON]] (M.E.D.)  
National Institute for Research and Development in Chemistry and Petrochemistry--ICECHIM, Evaluation and Conservation of Cultural Heritage Research Group, 060021 Bucharest, Romania; [EMAIL_ADDRESS]  
Joint Institute for Nuclear Research, 141980 Dubna, Russia; [EMAIL_ADDRESS] (B.A.B.); [EMAIL_ADDRESS] (S.E.K.); [EMAIL_ADDRESS] (D.P.K.); [EMAIL_ADDRESS] (A.V.B.)  
Kazan (Volga Region) Federal University, Insitute of Physics, Departament of Nuclear-Physical Materials Science, 420008 Kazan, Russia  
Duha State University, Faculty of Natural and Engineering Science, 141980 Dubna, Russia  
Institute of Multidisciplinary Research for Science and Technology, Valahiu University of Targoviste, 130004 Targoviste, Romania; [EMAIL_ADDRESS] (L.D.); [EMAIL_ADDRESS] (I.A.B.); [EMAIL_ADDRESS] (A.I.G.); [EMAIL_ADDRESS] (R.M.S.); [EMAIL_ADDRESS] (S.T.)  
Faculty of Sciences and Arts, Valahiu University of Targoviste, 130004 Targoviste, Romania  
Correspondence: [EMAIL_ADDRESS] (R.M.I.); [EMAIL_ADDRESS] (C.R.); Tel.: +40-745-763-615 (R.M.I.); +40-729-851-455 (C.R.)  
Received: 4 May 2020; Accepted: 27 May 2020; Published: 29 May 2020  
**Featured Application: This article may serve as a database for other research into mosaics and, also, as a guide for what methods may be applied.**  
The color characteristics, vibration spectra, phase and mineral composition, internal structural organization of several fragments of the ancient Roman mosaics from the Roman Mosaic Museum, Constanta, Romania were studied by non-destructive (Chromatic analysis, Neutron Diffraction, Neutron Tomography) and micro-invasive techniques (Optical Microscopy, X-ray Diffraction, Field Emission Scanning Electron Microscopy-Energy Dispersive X-ray Spectroscopy, Raman Spectroscopy, Wavelength Dispersion X-ray Fluorescence). These investigations were performed in order to characterize the original Roman mosaic fragments. The major and minor phase components of the studied mosaic fragments were determined, the crystal structure of the main phases was analyzed, and their three-dimension spatial arrangement was reconstructed. The similar composition of the major phases of all mosaic fragments can indicate a generic recipe for making mosaic elements, but minor phases were presumably added for coloring of mosaic pieces. Some degradation areas inside the volume of the mosaic fragments were found by means of neutron diffraction and neutron tomography methods. These degradation areas are probably related to the formation of iron hydroxides during chemical interactions of mosaic fragments with the sea and urban polluted atmosphere.  
Roman mosaic; non-destructive techniques; micro-invasive techniques; neutron diffraction; neutron tomography; cultural heritage; conservation/restoration