Distinguishing between calcites formed by different mechanisms using infrared spectrometry: archaeological applications

Infrared spectrometry is a well-established method for the identification of minerals. Due to its simplicity and the short time required to obtain a result, it can be practiced on-site during excavation using portable infrared spectrometers. However, the identification of a mineral may not be sufficient. For example, a lime plaster floor and a crushed chalk surface have a similar appearance and are composed of the same mineral – calcite. Here we exploit differences in the infrared spectra of geogenic, biogenic and pyrogenic calcites for the identification of each calcite type. The infrared calcite spectrum has three characteristic peaks in the region of 400–4000 cm⁻¹, designated ν₂, ν₃, and ν₄. When a calcite sample is ground, as part of the measurement preparation procedure, some grinding dependent changes will be revealed in the infrared spectrum. With additional grinding, the ν₃ peak narrows and the heights of the ν₂ and ν₄ peaks decrease, when both are normalized to the ν₃ height. By plotting the normalized heights of the ν₂versus the ν₄ of several grindings of the same sample, a characteristic trend line is formed for each calcite type. The trend lines of geogenic calcites have the shallowest slopes and highest ν₄ values when compared to pyrogenic calcites, which can be further divided to ash and plaster/mortar samples. This method can assist in distinguishing between the various calcites, and provide insights into homogeneity and preservation state of the calcitic materials in question.     

Iron Age hydraulic plaster from Tell es-Safi/Gath,Israel

Hydraulic plasters or mortars prior to the Roman period are rare. Here, we report the identification and characterization of 3000 year old (Iron Age) hydraulic plaster surfaces from the site of Tell es-Safi/Gath. This site, located in central Israel, was occupied almost continuously from prehistoric through modern times, and is identified as the Canaanite and Philistine city of Gath. A survey using an on-site Fourier transform infrared spectrometer (FTIR) identified the presence of amorphous silicates, in addition to calcite, in each of two superimposed plaster layers. This suite of minerals is characteristic of hydraulic plaster. An in-depth characterization of the plasters using FTIR, acid dissolution, X-ray fluorescence (XRF), X-ray powder diffractometry (pXRD), heating experiments and scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (SEM–EDS), shows that special silicate-containing minerals were brought from some distance to the site in order to produce these plaster surfaces. We therefore conclude that the plasters were deliberately produced, and were not the result of a fortuitous addition of local silicate minerals. A layer of around 150 μm thick enriched in carbonate hydroxylapatite was found in both plaster surfaces, and the same mineral was identified by infrared spectrometry in the surrounding sediments. This suggests that organic materials were used on these surfaces. These surfaces are among the oldest hydraulic plasters known.     

The 7th–9th Century Tantura E Shipwreck,Israel: construction and reconstruction

The Tantura E shipwreck was discovered in Tantura lagoon, Israel, in a water depth of 2.8 m, covered by 1 m of sand. It was a coaster that plied the Levant coast, dated to the 7th–9th centuries CE. It was recorded under water, but several components were studied on land, as well as the finds. The hull is of frame‐based construction, with flat floor timbers and a sharp turn of the bilge. The archaeological evidence, as well as modern design tools and regulations, suggests that Tantura E was c.12.5 m long, of 25 tonnes displacement, and could load c.17.5 tonnes.     

Differentiating between anthropogenic calcite in plaster,ash and natural calcite using infrared spectroscopy: implications in archaeology

Infrared spectroscopy provides information not only on the type of calcium carbonate polymorph, but also on the extent of atomic order. In calcite, three major infrared absorption peaks are identified: ν₃, ν₂, and ν₄. It was shown that the ratio between ν₂ and ν₄ bands reflects the order of the calcite crystal structure. In this paper we analyse this ratio in geologically formed calcites, archaeological plasters, modern plasters and experimentally prepared plasters. For the geological calcite, the values of the ν₂/ν₄ ratio are around 3, whereas for the experimentally prepared plasters, the values are around 6.5. The ν₂/ν₄ ratio for archaeological plasters varies from 3 to 6. This shows that a high ratio is indicative of disorder in the crystal, and implies that the calcite was formed from calcium oxide at high temperatures. It also implies that this disorder can be preserved for at least 14,000 years. The ν₂/ν₄ ratio of calcite from archaeological sites can thus be used to differentiate between anthropogenic calcite, such as in plaster, mortar and wood ash, from geogenic calcite, such as in limestone. The ratio may also be used to identify plaster or ash that still retains its original crystals and therefore carbon-14 content.     

Charles Eliot Norton,E.L. Godkin,and the Liberal Republicans of 1872

The Liberal Republican Party of 1872 combined ‘genteel’ intellectuals such as Charles Eliot Norton and E.L. Godkin with hardened politicos like Horace Greeley. It serves therefore as a window on the political thought of Norton and Godkin at a moment when their ideas were tested by exposure to the real world of practical politics. The two men's revulsion at the nomination of Greeley and the debasing of the reform cause exposed their underlying conservatism during this time.     

Social‐Civilian Apparatuses of Hamas,Hizballah, and Other Activist Islamic Organizations

The aim of this article is to examine the social‐civilian activities of activist Islamic organizations in general, and of the Palestinian Hamas and Lebanese Hizballah in particular. As opposed to the common approach in academic and semiacademic publications, some of them aiming to promote political and propagandist goals, this article claims that the connection between the organizations' social‐civilian activities and their military and political apparatuses is not so close, although it does exist indirectly, and that these activities come first and foremost to answer religious commandments and social needs. This conclusion arises from examining the religious and historical roots of Hamas's and Hizballah's social‐civilian apparatuses and from comparing them with those of parallel organizations that are nonviolent.     

Folded wheel-made oil lamps,standing pit burial caves and Judaean ethnic identity in the Hasmonean period

ABSTRACT

Two distinct archaeological phenomena appeared between the middle of the second century BCE and the middle of the first century: the Hasmonean folded wheel-made lamp and the standing pit burial cave. Following an examination of their dating, distribution, and social significance we suggest that this material culture was characteristic of the Jews in Judaea during this time and that it reflects the creation of an ethnic identity. The fact that the Hasmonean folded wheel-made lamp and the standing pit burial cave were typical of Jews in Judea indicates that they were ethnic features of Jewish society. By these means the Jews emphasized their dissimilarity from the rest of the population. The archaic appearance of the lamps and the burial caves, which replicates the cultural characteristics of the Kingdom of Judah during the monarchic/first Temple period, indicates that Jewish society in the Hasmonean period sought to legitimize its existence through the use of its former culture and memory.