High-resolution transmission electron microscopy (HRTEM) has shown regions of crystallites within noncrystalline matrices of three types of glass (volcanic glass, alkalic igneous glass, and synthetic, nuclear-waste-form glass) The volcanic glass fragments showed domains having 3-Å spacings. About 30% of the fragments of this glass showed localized lattice images, having spacings of 5, 7, 8, 10, 13, 14, 16, 19, and 20 Å, which also contain regular fringes having 3.3-Å separations. In the alkalic igneous glass fragments 3-Å domain structures were also noted as were localized lattice images having 7- and 12.5-Å spacings. Well-developed hollow spheres of primitive clays were present in both the volcanic and alkalic igneous glasses. Synthetic, nuclear-waste-foTm glass, fused at 1400°C and annealed at 550°C, showed locally ordered regions having 3.3-Å spacings. Low-angle X-ray powder diffraction showed major reflections at 8.5, 15–16, and 19 Å, which agree with some of the HRTEM measurements. These observations of domain structures, localized lattice images, primitive clays, and 14-Å clays in such noncrystalline glass matrices may contribute to an understanding of the growth of clay minerals. Such domains can apparently trigger the growth of clay products on the glass substrate.

Secondary minerals formed during simulated weathering of nuclear waste glasses have been identified by analytical electron microscopy. A complete description of the reacted glass, from the outermost surface in direct contact with the leachant solution to the reacting front that migrates into the bulk glass, was obtained. Manganese and iron oxyhydroxide phases and saponite were found to have precipitated onto the residual glass surface from the leachant solution. Iron-bearing smectite, serpentine, and manganese and uranium-titanium oxyhydroxides formed in situ in the glass in several distinct bands at different depths beneath the original surface. This sequential development of secondary phases displays a clear trend toward more order and crystallinity in the phases farthest from the reaction front and indicates that complete restructuring of the glass into crystalline phases did not occur at the interface with fresh glass. Additionally, the formation of a discrete uranium-bearing phase, as opposed to uranium uptake by precipitated phases, suggests that stable actinide phase formation rather than ion exchange may be a possible mechanism for retarding radionuclide release to the environment.

Perlite, which occurs at the contacts between dacite and lacustrine tuffs of Miocene age in the Guryongpo area, Korea, has undergone more sluggish and incomplete diagenetic alteration than the surrounding zeolitic tuffs. Alkali-clinoptilolite, mordenite, smectite, K-rich gel-like glass, low-cristobalite, and K-feldspar are characteristic diagenetic phases in the altered perlite.

Hydration of the glass to form perlite resulted in the expulsion of cations, mainly Na, from the glass into the pore fluid and in the relative enrichment of K in the perlite. Hydration of the glass also resulted in increased alkalinity of the pore fluid, which, in turn, affected the nature and behavior of subsequent glass dissolution. Textural observations and chemical data on the early diagenetic phases indicate a sequence of incongruent dissolution reactions, which depended on silica activity and alkalinity of the ambient pore fluid: Reaction (1) 12.5 perlitic glass + 3.88 K+ + 0.65 H+ + 15.4 H20 = smectite + 9.5 gellike glass + 4.03 Na+ + 0.25 Ca2+ + 10.55 H4SiO4 released Ca and silica which were consumed by reaction (2) perlitic glass + 0.1 Ca2+ + 0.1 H4SiO4 + 0.1 H+ + H20 = clinoptilolite + 0.1 K+ + 0.2 Na+. The paragenesis from glass via smectite to alkali zeolites in most glass-bearing rocks may be explained by a sequence of such dissolution reactions. Still later reactions involved the transition from less-silicic clinoptilolite to an assemblage of silicic Na-clinoptilolite + mordenite and the crystallization of the gel-like glass to K-feldspar.

The structure, chemistry and distribution of hydrothermal alteration and weathering products of feldspars and glass in 3 samples of Yucca Mountain tuffs (GSW G4 borehole at a depth of 1531 ft (464 m) and USW GU3 borehole at 1406 ft (426 m) from the Calico Hills Formation and USW G4 at a depth of 272 ft (82.4 m) from the Topobah Springs Member) were examined by high-resolution transmission electron microscopy (HRTEM) and analytical electron microscopy (AEM). Alteration products are of interest because they may influence the form and distribution of contaminants released from the proposed high-level nuclear waste repository. Samples from the Calico Hills Formation contain alkali-bearing aluminosilicate glass and its alteration products. Zeolites appear to have formed from compositionally similar glass by recrystallization, probably under hydrothermal conditions. Crystals are fibrous and frequently no more than a few tens of nanometers in diameter. Porous aggregates of few-nanometer-diameter, poorly crystalline silica spheres (probably opal C-T) develop adjacent to corroded glass surfaces and zeolite crystals. Finely crystalline Fe-rich smectites coat etched glass surfaces, zeolites and feldspar crystals and occur within opal-like silica aggregates. Microstructures in the clay-dominated coatings and details of smectite-glass interfaces suggest that clays grow in orientations controlled by heterogeneously retreating surfaces and from constituents released at associated glass dissolution sites. The alteration assemblage also includes finely crystalline hematite, goethite, Mn-oxide films and illite formed by alteration of muscovite. The zeolitized sample contains abundant opal-like silica whereas glass in the unzeolitized sample is weathered to smectite-like clays. These differences may be attributed to hydrological and consequent geochemical factors resulting from the higher porosity of zeolitized samples. Exsolved alkali feldspar, which occurs as micron-sized crystals in the Calico Hills Formation and as phenocrysts and in the groundmass of the devitrified Topobah Springs Member, are almost unaltered. Feldspar alteration is confined to cracks and grain boundaries, where minor, poorly crystalline, Fe-bearing aluminosilicate alteration products are developed. In these tuffs, most of the porosity, permeability, high surface area and capacity to affect solution chemistry are associated with products of glass alteration.

High-resolution transmission electron microscopy has revealed spherical and hemispherical structures on the surface of partly hydrated volcanic and synthetic glasses. These structures contrast with the bulk of the glass in showing lattice-fringe images indicative of the early stages of crystallization. Heavy-ion Rutherford scattering analysis of the noncrystalline volcanic glass indicates a structural water with hydrogen and deuterium. Depth profiles show that the glass grains contain structural water without adsorbed water on the surface. The presence of structural water in volcanic glass must be of interest to the formation of primitive clays. The spherical and hemispherical structures favor production of clay precursors in the presence of water.

Clay minerals in chilled or brecciated margins (altered glass) and massive inner crystalline parts (mesostasis) of three basalt-hawaiite bodies from Mururoa Atoll (French Polynesia) have been studied in order to compare their chemical and mineralogical compositions. Polyphase assemblages comprise di- and trioctahedral phases, both of which consist of non-expandable layers (chlorite, celadonite) and two types of expandable layers (saponite and Fe-rich smectite or ‘nontronite-like’ material). The presence of the Fe-rich clays is supported by the presence of the X-ray diffraction 060 peak at 1.51–1.52 Å and of the infrared absorption bands at 875 and 822 cm−1 (Fe3+-Al-OH and Fe3+-Fe3+-OH groups, respectively). The chemical composition of the Fe-rich smectites does not fit with the theoretical nontronite field. The layer charge averages 1 per Si4O10 making these Fe-rich smectites close to ‘celadonite-type’ clays. This could explain the presence of mixed-layer celadonite-smectite. Plotted in an M+/4Si vs. Fe/sum octahedral cations diagram, the chemical compositions of clay minerals in the mesostasis form a continuous field limited by the celadonite-high-charge nontronite-like smectite and chlorite end-members. The clay assemblages are different from those formed in hydrothermal systems or low-grade metamorphic conditions which are characterized by the sequence: saponite → randomly ordered chlorite-smectite mixed-layered minerals (MLMs) → corrensite → chlorite. The systematic presence of Fe-rich clays either in the altered chilled margins or in the massive inner parts of the basalt-hawaiite bodies (high-charge nontronite-like smectite and mixed-layer nontronite-celadonite) makes the Mururoa sea-mount a potential terrestrial analogue for Mars surface exploration.

In this article, the authors investigate the effectiveness of glass and metal recycling in Roman towns. The comparison of sealed primary deposits (reflecting what was in use in Roman towns) with dumping sites shows a marked drop in glass and metal finds in the dumps. Although different replacement ratios and fragmentation indices affect the composition of the assemblages recovered in dumps, recycling appears to have played a fundamental role, very effectively reintroducing into the productive chain most glass and metal items before their final discard. After presenting a case study from Pompeii, the authors examine contexts from other sites that suggest that recycling practices were not occasional. In sum, recycling should be considered as an effective and systematic activity that shaped the economy of Roman towns.

The small finds discovered during the 1948–1951 excavations by Katherine M. Kenyon and John B. Ward-Perkins at Sabratha were scattered after the 1950s and have taken some time to be re-assembled. The following report on the small objects includes material in silver, copper alloy, iron, lead, glass, semiprecious stones, clay and stone, with a separate report on the substantial bone artefact assemblage. As well as providing the basic data on the objects, some of which are unique to Roman Libya, efforts have been made to put them into their Empire-wide context.

This article analyses the phenomenon of glass in wall and floor opera sectilia from the Hellenistic period to Late Antiquity. This type of decoration was developed in Alexandria – as testified by archaeological finds – and then spread across the Greco-Roman world. In Rome the art created a backdrop for a series of displays – especially in imperial palaces and elite housing – that spanned the Imperial era. All the great metropolises were graced by it, including the new capital of the East, Constantinople, where it underwent a renewed flowering. This article analyzes the use of glass material mostly as inserts in marble compositions and, more rarely, in wholly vitreous compositions. It reflects upon the meaning of these different decorative products and attempts to interpret their economic, aesthetic, and symbolic implications.

Glass bangles are found in southern England and Wales from the mid-first century ad and become common in the north of England and southern Scotland in the late first century, before their numbers decline a century later. British bangles develop at a time of change, as Roman glassmaking practices were introduced across large areas of Britain, and as blown, transparent, colourless and naturally-coloured glassware became increasingly popular. In many communities, however, there was still a demand for strongly coloured opaque glass, including for bangles, and glassworkers devised ways of extending their supplies of opaque coloured glass. This study is based on over one hundred and fifty analyses of bangle fragments from sites in Wales, northern England and southern Scotland, spanning this transitional period. The bangle makers recycled coloured glass from imported vessels, and probably beads and bangle-making waste, to supplement supplies of fresh coloured glass. The novel methods used to modify and extend the coloured glass may derive from pre-Roman bead-making industries, and made use of widely available materials, including smithing hammerscale and possibly plant ashes. The results show the shifting balance of indigenous and Roman influences on different bangle types, depending on when and where they were made, and by whom.

Mutability—the ability to change form and substance—is a key feature of glass and metals. This quality, however, has proven frustrating for archaeological and archaeometric research. This article assesses the typological, chemical and theoretical elements of material reuse and recycling, reframing these practices as an opportunity to understand past behaviour, rather than as an obstacle to understanding. Using diverse archaeological data, the authors present case studies to illustrate the potential for documenting mutability in the past, and to demonstrate what this can reveal about the movement, social context and meaning of archaeological material culture. They hope that through such examples archaeologists will consider and integrate mutability as a formative part of chaînes opératoires.

Characterizing non-lethal damage within dry seeds may allow us to detect early signs of ageing and accurately predict longevity. We compared RNA degradation and viability loss in seeds exposed to stressful conditions to quantify relationships between degradation rates and stress intensity or duration. We subjected recently harvested (‘fresh’) ‘Williams 82’ soya bean seeds to moisture, temperature and oxidative stresses, and measured time to 50% viability (P50) and rate of RNA degradation, the former using standard germination assays and the latter using RNA Integrity Number (RIN). RIN values from fresh seeds were also compared with those from accessions of the same cultivar harvested in the 1980s and 1990s and stored in the refrigerator (5°C), freezer (−18°C) or in vapour above liquid nitrogen (−176°C). Rates of viability loss (P50−1) and RNA degradation (RIN⋅d−1) were highly correlated in soya bean seeds that were exposed to a broad range of temperatures [holding relative humidity (RH) constant at about 30%]. However, the correlation weakened when fresh seeds were maintained at high RH (holding temperature constant at 35°C) or exposed to oxidizing agents. Both P50−1 and RIN⋅d−1 parameters exhibited breaks in Arrhenius behaviour near 50°C, suggesting that constrained molecular mobility regulates degradation kinetics of dry systems. We conclude that the kinetics of ageing reactions at RH near 30% can be simulated by temperatures up to 50°C and that RNA degradation can indicate ageing prior to and independent of seed death.