Microwear Analysis of Retouched Glass Fragments from Fortlet Miñana,Azul, Argentina, 1860–1863

This paper presents the results of a microscopic analysis conducted on supposedly retouched glass fragments that were likely used as tools. The pieces were recovered in a series of excavations performed at the historical site of Fortlet Miñana (1860–1869), a military settlement used during the war against the Indians on the southern border of Buenos Aires province, Argentina. The use of glass as raw material in archaeological sites of the historic period has frequently been reported in the Pampas and Patagonian regions. In this paper we present a review of ethnohistoric and ethnographic sources concerning the use of glass side scrapers, end scrapers, and arrowheads by aboriginal groups throughout the world. In order to perform the analysis, the glass fragments from Fortlet Miñana were compared to a series of experimental pieces on which traces of deliberate use on two kinds of raw material, wood and hide, were identified. The experimental approach and the microscopic analysis demonstrate that the retouched glass fragments recovered at Fortlet Miñana were not used as tools. Therefore, we conclude that microscopic analysis is of significant use to all researchers working with materials of this kind.     

Santa Maria di Collemaggio Church (L’Aquila,Italy): Historical Reconstruction by Non-Destructive Testing Techniques

The main goal of this work was the non-destructive testing (NDT) of an ancient fresco (15th century) preserved in the Santa Maria di Collemaggio Church (L’Aquila, Italy) and damaged after the 2009 earthquake. Active infrared thermography (IRT), near-infrared (NIR) reflectography and ultraviolet imaging (UV) were used. In addition, the state of the fresco prior to the earthquake was analyzed by electronic speckle pattern interferometry (ESPI), digital speckle correlation (DSC), raking light, tap, and chemical NDT techniques. The use of these techniques was important for the monitoring of new damages and for a comparison between the results over the years. Square heating thermography (SHT) data were processed using principal component thermography (PCT) and pulsed phase thermography (PPT) algorithms, in order to improve the defects’ signature and to reduce the impact of non-uniform heating and emissivity variations due to the painting’s pigments. A multi-analysis approach, segmentation operators and a specific data correlation method emphasize the overall study of the fresco. Furthermore, the facade and the high altar area were inspected by passive thermography and ground-penetrating radar (GPR), respectively. In the present case, the combined use of NDT techniques was useful to fill in the gaps in the construction history of the building.