CARATTERIZZAZIONE MINERALOGICA E COLORIMETRICA DI OCRE

Corso di Laurea in Scienze e Tecnologie per la Conservazione dei Beni Culturali presso l’Università “Sapienza” di Roma.

Anno Accademico 2013-2014

 

Laureanda: Gaia Appolloni
Relatore:Prof.ssa Adriana Maras, Dipartimento di Scienze della Terra-Università degli Studi di Roma “La Sapienza”.
Correlatore:Dott.ssa Michela botticelli, Dipartimento di Scienze della Terra-Università degli Studi di Roma “La Sapienza”.

Subject of this study is the mineralogical and colorimetric characterization of eleven samples, still classified as "limonite" in the Museum of Mineralogy, University "Sapienza" of Rome (MMUR). The limonite is a rock composed of various oxides and hydroxides of iron, mainly goethite, maghemite, hematite, lepidocrocite,pitticite, the jarosite group minerals, etc.. The limonite derived from the oxidation of iron minerals (for example pyrite, hematite) which can preserve the form (pseudomorphosis). Containing crystalline phases and amorphous, hydrated and not, in varying proportions, its mineralogical characterization is quite complex. The limonite has varying in color from brown to yellow, so it was used as a pigment which is known as yellow ocher. Italy is rich in deposits of ocher, which are exported as natural colored earth. 
The samples, all Italian, come from six different sites: Elba Island, Campo Becco mine to Carloforte, Monte della Vena to Giglio island, Monte Leone to Spoleto (Perugia), the volcanic rocks of the Veronese and Pietrasanta (Lucca ). These were chosen to test whether via X-ray diffractometry is possible to identify the major components, if present the various locations or less the same phases, finally, if the colorimetric properties of the samples, together with the FTIR spectroscopy can help to characterize and distinguish the origin the natural ochresfrom synthetic samples made in the laboratory. 

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