Artefacts from Ban Chiang, Thailand: Pre-metal Age cord-marked pottery

Abstract Pottery excavated from the archeological UNESCO world heritage site Ban Chiang in Thailand stem from distinct periods. Black vessels with cord-mark design from Pre-metal Age (ca. 3000–1000 BC), Bronze Age pottery (ca 1000–300 BC) with yellow-brown surface and Iron Age samples (ca. 300 BC–200 AD) with red pictorial surface patterns. In a previous work [Bismayer U., Srilomsak S., Treekamol Y., Tanthanuch W., Suriyatham K. Artefacts from Ban Chiang, Thailand: pottery with hematite-red geometric patterns. Z. Kristallogr. 2020, 235, 559–568] we studied the mineralogical composition and their surface colour materials of shards from Bronze and Iron Age. In this work we focus on bulk features of the dark Pre-metal Age cord-marked ceramic shard PSN2-S10E13 and compare its elemental and mineralogical composition with bulk composition of sample 5412-S6E15 from Bronze Age. Experimental techniques are electron microprobe, X-ray powder diffraction, FTIR spectroscopy, optical microscopy and X-ray tomographic microscopy (XTM). Sample PSN2-S10E13 contains more quartz than 5412-S6E15. In the bulk of the Pre-metal Age shard, diffraction signals of mullite occur, indicating higher firing temperatures compared to the younger sample. Phyllosilicate signals are seen in FTIR spectra of both shards. E-modes of quartz dominate FTIR spectra of both samples. Optical thin sections show voids around micro-particles in PSN2-S10E13 and XTM indicates that the pore volume percentage of sample PSN2-S10E13 is higher than in 5412-S6E15. Because of the large age gap to younger samples from Ban Chiang, the proper age of our oldest sample PSN2-S10E13 was determined using an accelerator mass spectrometer (AMS) by simultaneous 14C/12C and 13C/12C isotope ratio measurements which yielded a radiocarbon age of 3609 ± 29 BP (resp. 1659 ± 29 BC).