Raman Spectroscopic Study of the Mineral Thorikosite Pb₃(OH)(SbO₃,AsO₃)Cl₂: A Mineral of Archaeological Significance

ABSTRACT

The mineral thorikosite Pb₃(OH)(SbO₃,AsO₃)Cl₂ is named after the ancient city of Thorikos, in the region of Attica, where the ancient mine sites dating back to the bronze ages are found. Raman spectra of the antimonite-bearing mineral thorikosite Pb₃(OH)(SbO₃,AsO₃)Cl₂ were studied and were related to the structure of the mineral. Two intense Raman peaks were observed at 596 and 730 cm⁻¹ and were assigned to the Sb³⁺O₃ and As³⁺O₃ stretching vibrations. A peak at 1085 cm⁻¹ is assigned to the Sb³⁺OH deformation mode. Raman band at 325 cm⁻¹ is assigned to an OAsO bending vibration of the As³⁺O₃ units, and the bands at 269 and 275 cm⁻¹ are attributed to the OSbO bending modes of the Sb³⁺O₃ units. The intense Raman bands at 112 and 133 cm⁻¹ are associated with PbCl stretching modes. Minerals such as nealite and thorikosite are minerals of archaeological significance. Yet no spectroscopic studies of these minerals had been undertaken.

KEYWORDS:

• antimonite
• archaeology
• coquandite
• nealite
• Raman spectroscopy
• thorikosite

ACKNOWLEDGMENTS

The authors are grateful for the financial and infrastructure support of the Queensland University of Technology Chemistry Discipline, Faculty of Science and Technology. The authors thank the Australian Research Council (ARC) for funding the instrumentation.