Introduction Black gloss ware had been produced since the 5 th century B.C. in many sites around the Mediterranean. This type of pottery consists of a clayey body coated with black gloss which is characterized by different optical effects. Matt black, shining black, metallic black, and bluish black glosses are the more widespread gloss types in Tuscan archaeological sites. Some archaeological and archaeometric questions linked to these black glosses are still a matter of debate. To date, no clear evidences link one type of gloss to a partic- ular site; moreover, few information of production site location are available while several types of glosses are widespread in a vast circum-mediterranean area. Many authors have performed archaeological, chem- ical, and mineralogical studies on ancient pottery. For a detailed revision of papers and an exhaustive presentation of methods and issues in archaeometry the authors refer to Velde & Druc (1999; and references therein). X-ray techniques and optical and scanning electron microscopy (SEM) have been commonly utilized to deter- mine original source materials, firing temperatures, and manufacturing processes of both ceramic body and coat- ings. Prehistoric pottery has been investigated by Mata et al. (2002) using X-ray diffraction (XRD), SEM and transmission electron microscope (TEM). They determined the firing temperature and the duration of the process based on the mineralogical assemblage and texture in the body. Greek and Roman technology for the preparation of Attic and Italian pottery has been investigated by Kingery (1991) through electron microprobe (EMP) analysis. He investi- gated the starting materials for both the body and the coating and he pointed out that the fine suspension of clays employed for the gloss was obtained either through simple sedimentation or by adding goethite or other Fe-rich addi- tives. Studies have been also carried out on lustre and gloss. Attic glosses have been chemically investigated since the paper of Tite et al. (1982). Microchemical, electron Eur. J. Mineral. 2004, 16, 493-503 Tuscan black glosses:A mineralogical characterization by high resolution techniques GIOVANNA GIORGETTI*, ELISABETTA GLIOZZO and ISABELLA MEMMI Dipartimento di Scienze della Terra, Università di Siena, via Laterina, 8, I-53100 Siena, Italy Abstract : Tuscan black glosses on ancient pottery have been characterized using high resolution techniques. Ancient (4 th -1 st century B.C.) pottery from southern and northern Tuscany is coated with black glosses which show different visual appearance. Misfired red-black, matt, shining, metallic, and bluish black glosses have been studied with X-ray diffraction, scanning and trans- mission electron microscopes to establish their mineralogical, textural and chemical characteristics. The glosses are chemically homogeneous and they are all comprised of a Si-Al rich, amorphous matrix where nanometer-sized crystals of different nature are embedded. Crystals occur both as euhedral grains and as grains with a high aspect ratio. The misfired gloss contains hematite as the only mineral phase, both in the red and black portion of the coating. The matt black gloss contains mainly homogeneous hercynite crystals. In a small portion of the gloss, few magnetite crystals have been detected. However, no gradual variations either along or perpendicular to the gloss layer have been observed. Magnetite is the only mineral phase occurring in the shining metallic black gloss. The bluish-black gloss shows spinel grains with variable characteristics. Most grains are comprised of homogeneous hercynite with magnetite in solid solution. Other crystals are zoned: the core has hercynitic composition with relatively high content in magnetite, ulvospinel, and spinel s.s. in solid solution; Al and Mg increases towards the rim. These results clearly indicate that microanalytical techniques provide accurate mineralogical and microtextural characteriza- tions at the nanometer scale. It has been shown that visually different glosses have different mineralogy which are mainly caused by different oxygen fugacities (f O 2 ) during firing. Key-words: Tuscany, archaeology, ancient black gloss, HRTEM, spinels. 0935-1221/04/0016-0493 $ 4.95 © 2004 E. Schweizerbart’sche Verlagsbuchhandlung. D-70176 Stuttgart DOI: 10.1127/0935-1221/2004/0016-0493 *E-mail: giorgettig@unisi.it