O tratamento térmico da ametista: Alto Bonito, Garimpo das Pedras, Carajás, Pará

Abstract

In the early 1980s, a group of sourdoughs settled in the Alto Bonito farm, in the municipality of Marabá (Serra dos Carajás region, Pará), where a significant occurrence of amethyst crystals was discovered. It begins the exploration of the amethyst and its thermal transformation, by heating, in citrine. Since prehistory, the human groups that attended the Serra dos Carajás use the prismatic crystals of hyaline and amethyst quartz, which were frequently transformed by heat treatment into citrine (Rodet 2015; Magalhães 2016; Rodet et al. in press). The main objectives of this work are: to understand the operating chains of current exploration and thermal transformation of the amethyst, with emphasis on the choices, techniques, methods and instruments used to finally relate it to prehistory. This is, in fact, the first time we observe the heat treatment of lithic industries in Brazilian prehistoric sites. On the other hand, few are the current groups that still chip and, rarely, are the groups that use thermal treatment to transform rocks or minerals. In this sense, in the region of study there is a group of prospectors who explore the amethyst, flake it and treat it thermally transforming it into citrine. In order to better understand how the process is carried out today (and also in the past), it seemed important to us to work together with such a group. For this, the ethnographic research consisted of a visit to the sourdough communities, as well as interviews about the various stages of the productive process. The theoretical orientation of the work is based on the concepts of the chaîne opétaroire, the study of techniques and gestures, as well as the gender issues that involve production (Mauss 1947; Leroi Gourhan 1964; Inizan et al. 1995, 2017; Roqué-Rosell et al. 2011; Pelegrin 2011; Bruschini 2007). The results led to an understanding of the intentions of the productions, the techniques and the instruments of modern knapping; heat treatment and division of labor. The comparison with the prehistoric industries allowed a better understanding of the latter.