Abstract
ABSTRACT This paper reports on an unknown yellowish mineral compound found in an archaeological context from Chorrillos cemetery (Calama, Chile) dating to the Early Formative period (800 - 200 B.C.). We used optic microscopy, SEM, EDX, 1 H- RMN, 13 C-RMN, and infrared (IR) and Raman spectroscopy to tease out the chemical and molecular composition of the sample. The microscopic images show amorphous yellowish granulates with heterogeneous chemical surfaces. 1 H- RMN and 13 C-RMN negative results show that the sample is free of organic matter. The SEM and EDX indicate the presence of arsenic and sulfur in the sample. The IR and Raman analyses suggest the presence of orpiment which is a toxic yellow arsenic sulfide mineral. Keywords: Pigments, Raman spectroscopy, SEM-EDX, Chorrillos, Northern Chile. e-mail: jpabloogalde@yahoo.es INTRODUCTION Instrumental analyses of pigment usage have a significant value to play in many disciplines, such as natural resources, prehistoric artistic expression, archaeology and art history. It is a useful tool to identify and characterize pigments, elemental chemical composition, toxicity, usage, etc. Microsampling and non-destructive techniques are also important variables to consider when dealing with cultural patrimony and unique objects while pursuing chemical characterization and analyses of ancient samples
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