Trends in Colouring Blue Glass in Central Europe in Relation to Changes in Chemical Composition of Glass from the Middle Ages to Modern Age

The study deals with the development of the chemical composition of blue glass from the 13th to the 19th century in the region of Bohemia (Central Europe). Nearly 100 glass samples (colourless, greenish, and blue) were evaluated by an XRF method to distinguish the colouring components of blue glass. As early as in the 13th century, blue glass based on ash containing colouring ions of Co and Cu was produced here. To achieve the blue colour of glass, a copper-rich raw material was most likely applied. This information significantly complements the existing knowledge about glass colouring in the Middle Ages, as the glass of later periods was typically coloured with raw materials containing cobalt.

Reply to Blair

Blair provides a thorough review of data he claims stands in opposition to our narrative concerning the origins of IIa40/Early Blue glass trade beads and their presence in arctic Alaska prior to Columbus’ initial voyage. He employs three lines of evidence: historical and archaeological data, Instrumental Neutron Activation Analysis, and radiocarbon dating. Our reply addresses his application of these data sets, clarifying his use of our data to arrive at his conclusions. While we continue to disagree with Blair, we do wish to acknowledge his time spent on debating the issue thereby furthering all of our understanding on this topic.

Middle Bronze Age Long Distance Exchange through Europe and Beyond

The introduction of the folding stool and the single-edged razor into Southern Scandinavia, as well as the testimony of chariot use during the Nordic Bronze Age Period II (1500-1300 BC), give evidence of the transfer of ideas from the Mediterranean to the North. Recent analyses of the chemical composition of blue glass beads from well-dated Danish Bronze Age burials have revealed evidence for the opening of long distance exchange routes around 1400 BC between Egypt, Mesopotamia and South Scandinavia. When including comparative material from glass workshops in Egypt and finds of glass from Mesopotamia, it becomes clear that glass from those distant lands reached Scandinavia. The routes of exchange can be traced through Europe based on finds of amber from the North and glass from the South.

Polyhedron Seals of the Transcaucasian Origin Dated 2nd – 1st CC BC from the Burials of the Nomads of Asian Sarmatia of the 1st – First Half of the 2nd Century AD

The article features the gem of rather rare forms, namely so-called prisms, polyhedra, scaraboids and bifacial gems which were found in the burials of the Asian Sarmatia nomads. The author describes an attempt to attribute seals in the form of polyhedra from Sarmatian burials dated back to the 1st – first half of the 2nd century AD within the Lower and Upper Don and the Lower Volga regions. Polyhedra belong to the forms of gems, which became widespread in the Classical era, both among Greek and so-called Greek-Persian gems. In the 2nd – 1st centuries BC the seals in the form of polyhedra were widely distributed across the Caucasus and, especially, in Transcaucasia region. According to the finds, they are represented by numerous items made of carved stone, as well as of dark blue glass, milky white and greenish color. Moreover, there are also known rectangular forms of prints of such seals on the bulls, in particular which were excavated from the palace at Dedoplis Gora in Caucasian Iberia, dated to the 1st century BC – 1st century AD. The analysis of the shapes, materials and subjects of the images on the seals from the Sarmatian burials considered in the current article suggests that they were made in Transcaucasian workshops of the 2nd – 1st centuries BC. The probable Transcaucasian origin of the seals and their dating to the late Hellenistic period are an indirect confirmation of the hypothesis previously expressed by the author about the early cylindrical, conical seals and scaraboids of the mid-2nd – mid-1st millennium BC found in Sarmatian burials of the 1st century BC – 2nd century AD, originating from the sanctuaries of Transcaucasia.

An Archaeometallurgical Explanation for the Disappearance of Egyptian and Near Eastern Cobalt-Blue Glass at the end of the Late Bronze Age

A recent compositional study of Egyptian cobalt-blue glass from museum collections in Japan (18th Dynasty) and from the site of Dahshur (18th and 19th-20th Dynasties) concluded that a new source of cobalt was exploited for the later Dahshur glass, thereby suggesting that glass production continued into the Ramesside period (Abe et al. 2012). It is shown in the current article that some of this 18th Dynasty glass and the majority of the 19th-20th Dynasty glass had been recycled, not only supporting the general consensus that glass production virtually disappeared by 1250 BC, but that the cobalt source did not necessarily change. It is further proposed, however, that the generally accepted cobalt source for Egyptian glass was not the alum deposits of Egypt's Western Desert, but derived from cobaltiferous siliceous ores, possibly from central Iran. Re-analysis of the compositions of cobalt-blue glass frit found at Amarna, as well as Egyptian and Mesopotamian glass, suggests that the cobalt colourant was a by-product of silver extraction from these ores and can therefore be considered as a concentrated cobalt glass slag, which travelled in the form of a frit to glass producers who added it to locally derived base glasses and/or their precursors. Experiments conducted on ore containing cobalt-nickel arsenides with native silver demonstrate that not only can silver be extracted and that concentrated cobalt glass can be produced simply by adding a flux, but that some components of the ore partition preferentially into the silver or the glass slag, thereby weakening their associations with the other components in archaeological glass. Treating the cobalt-blue colourant as a slag composed of the gangue of a smelting system provides an explanation for the unique elevated levels of alumina and lower levels of potash found in cobalt-blue glasses, as well as providing an explanation for the cessation of cobalt exploitation at the end of the Late Bronze Age. It is suggested that the exhaustion of native silver and siliceous silver ore deposits during the Bronze Age, with argentiferous lead ores becoming the main source of silver, depleted the amount of cobalt available, thereby reducing the amount of glass produced which, in turn, led to increases in recycling during the New Kingdom period.

An Asander’s Gold Stater with Magic Graffito and a Labrys from the Settlement Tsemesskaya Roscha

The article is a publication of two remarkable votives found during the archaeological survey of the sacrificial complex in the Bosporan fortified settlement Tsemesskaya Roshcha. The first find is a gold stater of the Bosporan King Asander marked with regnal year 8. Gold staters of Asander with the 8th year of his reign were unknown before the discovery of such a specimen at the settlement Kara-Tobe in 2006. Thus, the presented coin found in 2013 is the second known example. The coin was used as an amulet-apotropaeos with the magic graffito in form of a pentagram and the letter Λ (lambda) and also a blue glass-eye bead were sacrificed as votives to Apollo and Zeus (?), while the garrison was leaving the fortress. Apart from these goods, an iron double-axe was found at some distance from the sacrifice. It may well be that the labrys is also a ritual artifact or a votive, although it is not directly related to the sacrificial complex with the gold coin-amulet.