Applying thermal demagnetization to archaeological materials: A tool for detecting burnt clay and estimating its firing temperature.

Burnt materials are very common in the archaeological record. Their identification and the reconstruction of their firing history are crucial for reliable archaeological interpretations. Commonly used methods are limited in their ability to identify and estimate heating temperatures below ~500°C and cannot reconstruct the orientation in which these materials were burnt. Stepwise thermal demagnetization is widely used in archaeomagnetism, but its use for identifying burnt materials and reconstructing paleotemperatures requires further experimental verification. Here we present an experimental test that has indicated that this method is useful for identifying the firing of mud bricks to 190°C or higher. Application of the method to oriented samples also enables reconstruction of the position in which they cooled down. Our algorithm for interpreting thermal demagnetization results was tested on 49 miniature sun-dried "mud bricks", 46 of which were heated to a range of temperatures between 100°C to 700°C under a controlled magnetic field and three "bricks" which were not heated and used as a control group. The results enabled distinguishing between unheated material and material heated to at least 190°C and accurately recovering the minimum heating temperature of the latter. Fourier-Transform Infrared Spectroscopy (FTIR) on the same materials demonstrated how the two methods complement each other. We implemented the thermal demagnetization method on burnt materials from an Iron Age structure at Tell es-Safi/Gath (central Israel), which led to a revision of the previously published understanding of this archaeological context. We demonstrated that the conflagration occurred within the structure, and not only in its vicinity as previously suggested. We also showed that a previously published hypothesis that bricks were fired in a kiln prior to construction is very unlikely. Finally, we conclude that the destruction of the structure occurred in a single event and not in stages over several decades.

Osmium isotope analysis as an innovative tool for provenancing ancient iron: A systematic approach.

The innovation of iron production is often considered one of the greatest technological advances in human history. A reliable provenancing method for iron is instrumental for the reconstruction of economic, social and geo-political aspects of iron production and use in antiquity. Although the potential of osmium isotopes analysis for this purpose has been previously suggested, here we present for the first time the results of osmium isotope analysis of ores, bloom and metal obtained from a set of systematic, bloomery iron-smelting experiments, utilizing selected ores from the Southern Levant. The results show that the 187Os/188Os ratio is preserved from ore to metal, with no isotopic fractionation. In addition, enrichment/depletion of osmium content was observed in the transition from ore to metal and from ore to slag. This observation has potential significance for our ability to differentiate between the various processes and sheds light on the suitability of various production remains for this method, which emerges as a robust and promising tool for the provenancing of archaeological ferrous metals.

Correction: Earliest evidence for equid bit wear in the ancient Near East: The "ass" from Early Bronze Age Tell es-Sâfi/Gath, Israel.

[This corrects the article DOI: 10.1371/journal.pone.0196335.].

Earliest evidence for equid bit wear in the ancient Near East: The "ass" from Early Bronze Age Tell es-Sâfi/Gath, Israel.

Analysis of a sacrificed and interred domestic donkey from an Early Bronze Age (EB) IIIB (c. 2800-2600 BCE) domestic residential neighborhood at Tell es-Sâfi/Gath, Israel, indicate the presence of bit wear on the Lower Premolar 2 (LPM2). This is the earliest evidence for the use of a bit among early domestic equids, and in particular donkeys, in the Near East. The mesial enamel surfaces on both the right and left LPM2 of the particular donkey in question are slightly worn in a fashion that suggests that a dental bit (metal, bone, wood, etc.) was used to control the animal. Given the secure chronological context of the burial (beneath the floor of an EB IIIB house), it is suggested that this animal provides the earliest evidence for the use of a bit on an early domestic equid from the Near East.

The Earliest Lead Object in the Levant.

In the deepest section of a large complex cave in the northern Negev desert, Israel, a bi-conical lead object was found logged onto a wooden shaft. Associated material remains and radiocarbon dating of the shaft place the object within the Late Chalcolithic period, at the late 5th millennium BCE. Based on chemical and lead isotope analysis, we show that this unique object was made of almost pure metallic lead, likely smelted from lead ores originating in the Taurus range in Anatolia. Either the finished object, or the raw material, was brought to the southern Levant, adding another major component to the already-rich Late Chalcolithic metallurgical corpus known to-date. The paper also discusses possible uses of the object, suggesting that it may have been used as a spindle whorl, at least towards its deposition.