Laterite nodules: A credible source of iron ore in iron age northeast Thailand?

Abstract

The advent of iron metallurgy changed the course of prehistoric Thailand. There is, however, little information on the nature of iron production and the extent to which locally abundant and easily quarried lateritic iron may have been the ore source. For northeast Thailand archaeological sites, the presence of both iron slag and laterite iron nodules within and surrounding these sites has widely been assumed to represent localized smelting using locally sourced iron ore. This interpretation is, however, based on untested laterite-equals-ore and slag-equalssmelting equations. This paper tests these assumptions by examining the chemistry of the lateritic iron nodules from two archaeological sites. At one site, the laterite is not a credible ore source and iron working probably comprised only smithing. Local laterite at the other site may be a usable ore. We conclude that, in northeast Thailand, the use of local laterite as an ore source cannot be assumed and that presence of both laterite and slag is not necessarily evidence for prehistoric smelting.

Seasonal Patterns of Fine Root Production and Turnover in a Mature Rubber Tree (Hevea brasiliensis Müll. Arg.) Stand- Differentiation with Soil Depth and Implications for Soil Carbon Stocks

“…Silt content was similar in all soil layers throughout the soil profile (100 g kg -1 ) while sand decreased to 700 g kg -1 at a depth of 1.0 m. From 100 to about 4.0 m, these properties remained fairly stable. The laterite layer was found at a depth of 6.0–7.0 m, as previously observed in this region ( Cawte and Boyd, 2010 ). The water table was not found within the first 7 m of the profile, even during the rainy season.…”

Multi-element characterization of archaeological floors at the prehistoric archaeological sites at Ban Non Wat and Nong Hua Raet in Northeast Thailand

“…McGrath (2001) argued that the distribution of iron nodules within the site sediments is best explained by their being deposited on the mound rather than being formed in situ; this process at Ban Non Wat was probably largely unintentional, possibly linked to the import of alluvial sediments for many functions, including iron smelting. Presence of both iron slag and laterite iron nodules within and surrounding the archaeological sites at northeast Thailand has widely been assumed to represent localized smelting using locally sourced iron ore, although this is hard to demonstrate with certainty (Cawte and Boyd, 2010). Importantly, the iron signatures in the hard floor sediments do not indicate any significant difference from the rest of the site, suggesting that these features were not specifically associated with an iron-working activity.…”

The Excavation of Iron Age Working Floors and Small-Scale Industry at Ban Non Wat, Thailand

“…Together, these finds suggest a metal working furnace where the 'narrow space' may have accommodated an inlet for an oxygen supply needed to achieve the high temperatures required for smithing. Recent research on metallurgy at BNW indicates that smithing was a more common activity than smelting (see Cawte and Boyd 2010).…”