On metal and ‘spoiled’ wine: analysing psimythion (synthetic cerussite) pellets (5th–3rd centuries BCE) and hypothesising gas-metal reactions over a fermenting liquid within a Greek pot

A Pb-based synthetic mineral referred to as psimythion (pl. psimythia) was manufactured in the Greek world at least since the 6th c BCE and routinely by the 4th c BCE. Theophrastus (On Stones, 56) describes its preparation from metallic Pb suspended over a fermenting liquid. Psimythion is considered the precursor of one of western art’s most prominent white pigments, i.e. lead white (basic lead carbonate or synthetic hydrocerussite). However, so far, and for that early period, published analyses of psimythia suggest that they consisted primarily of synthetic cerussite. In this paper, we set out to investigate how it was possible to manufacture pure cerussite, to the near exclusion of other phases. We examined the chemical and mineralogical composition (pXRF/XRD) of a small number of psimythion pellets found within ceramic pots (pyxis) from Athens and Boeotia (5th–4th c BCE) in the collection of the National Archaeological Museum (NAM), Athens. Analyses showed that the NAM pellets consisted primarily of Pb/cerussite with small amounts of Ca (some samples) and a host of metallic trace elements. We highlight the reference in the Theophrastus text to ‘spoiled wine’ (oxos), rather than ‘vinegar’, as has been previously assumed, the former including a strong biotic component. We carried out DNA sequencing of the pellets in an attempt to establish presence of microorganisms (Acetic Acid Bacteria). None was found. Subsequently, and as a working hypothesis, we propose a series of (biotic/abiotic) reactions which were likely to have taken place in the liquid and vapour phases and on the metal surface. The hypothesis aims to demonstrate that CO2 would be microbially induced and would increase, as a function of time, resulting in cerussite forming over and above hydrocerussite/other Pb-rich phases. Psimythion has for long been valued as a white pigment. What has perhaps been not adequately appreciated is the depth of empirical understanding from the part of psimythion manufacturers of the reactions between abiotic and biotic components within ‘oxos’/pot, as key drivers of minerals synthesis. Ultimately, psimythion manufacture may rest in understanding the nature of ‘oxos’, antiquity’s relatively little researched strongest acid.

Colour and Ink Characterization of Ottoman Diplomatic Documents Dating from the 13th to the 20th Century

This study investigates the colours and inks used in diplomatic documents of the Ottoman Empire dating from the 13th to the 20th century. Elemental and spectroscopic analyses were carried out on more than 150 documents using μ-XRF, Raman and FTIR spectroscopy; 10 documents were selected representatively for each century. In addition to the characterization of colour and ink, their use and distribution through the centuries is discussed. Analysis showed the presence of minium, vermilion, red ochre and cochineal (red pigments); lapis lazuli (ultramarine blue), azurite (blue verditer), Prussian blue and smalt (blue pigments); malachite and green earth (green pigments); massicot and yellow lead (yellow respectively orange pigments) and basic lead carbonate and zinc oxide (white pigments). All illuminations were ornamented with gold to demonstrate the power of the Empire and the Emperor. Texts were written in iron gall- and carbon-based black ink (carbon black/soot), cochineal (red) ink and gold.

Hydrocerussite-related minerals and materials: structural principles, chemical variations and infrared spectroscopy

White lead or basic lead carbonate, 2PbCO3·Pb(OH)2, the synthetic analogue of hydrocerussite Pb3(OH)2(CO3)2, has been known since antiquity as the most frequently used white paint. A number of different minerals and synthetic materials compositionally and structurally related to hydrocerussite have been described within the last two decades. Herein, a review is given of general structural principles, chemical variations and IR spectra of the rapidly growing family of hydrocerussite-related minerals and synthetic materials. Only structures containing a hydroxo- and/or oxo-component,i.e.which are compositionally directly related with hydrocerussite and `white lead', are reviewed in detail. An essential structural feature of all the considered phases is the presence of electroneutral [PbCO3]0cerussite-type layers or sheets. Various interleaved sheets can be incorporated between the cerussite-type sheets. Different sheets are stacked into two-dimensional blocks separated by the stereochemically active 6s2lone electron pairs on Pb2+cations. Minerals and synthetic materials described herein, together with a number of still hypothetical members, constitute a family of modular structures. Hydrocerussite, abellaite and grootfonteinite can be considered to constitute a merotype family of structures. The remaining hydrocerussite-related structures discussed are built on similar principles, but are more complex. Structural architectures of somersetite and slag phase from Lavrion, Attica, Greece, are unique for oxysalt mineral structures in general. Thus, the whole family of hydrocerussite-related phases can be denoted as a plesiotype family of modular structures. The crystal structures of hydrocerussite from Merehead quarry, Somerset, England, and of its synthetic analogue, both determined from single crystals, are reported here for the first time. The results of the infrared (IR) spectroscopy show that this method is useful for distinguishing several different minerals related to hydrocerussite and their synthetic analogues.