Calcium Antimonate Research Articles

Antimony mobility in soil near historical waste rock at the world's largest Sb mine, Central China

Soil near waste rock often contains high concentrations of antimony (Sb), but the mechanisms that mobilize Sb in a soil closely impacted by the waste rock piles are not well understood. We investigated these mobility mechanisms in soils near historical waste rock at the world's largest Sb mine. The sequential extraction (BCR) of soil reveal that over 95 % Sb is present in the residual fraction. The leached Sb concentration is related to the surface protonation and deprotonation of soil minerals. SEM-EDS shows Sb in the soil is associated with Fe and Ca. Moreover, X-ray absorption spectroscopy (XAS) results show Sb is predominantly present as Sb(V) and is associated with Fe in the form of tripuhyite (FeSbO4) as well as edge- and corner-sharing complexes on ferrihydrite and goethite. Thus, Fe in soils is important in controlling the mobility of Sb via surface complexation and co-precipitation of Sb by Fe oxides. The initially surface-adsorbed Sb(V) or co-precipitation is likely to undergo a phase transformation as the Fe oxides age. In addition, Sb mobility may be controlled by small amounts of calcium antimonate. These results further the understanding of the effect of secondary minerals in soils on the fate of Sb from waste rock weathering and inform source treatment for Sb-contaminated soils.

Fragments of luxury: Opaque glass from the Palace of Mystras, Greece

The present study focuses on the analysis of nine opaque or translucent glass samples of white, grey/blue and red colour, recovered from the Palace Complex of Mystras in southern Peloponnese, Greece. Their date cannot be determined with specificity but has to span between the mid-13th and mid-19th c. AD, the period since the construction of the site and throughout its continuous use as the administrative centre of the Despotate of Mystras. The extremely rare occurrence of opaque glass vessels of this period in Greece, as well as the recovery of most samples within Building E of the Complex, suggest that the samples were precious objects, possibly owned by high ranking members of the Palace. A multi-technique approach, including Optical microscopy, SEM/EDS, Raman spectroscopy and TEM analysis, was implemented in order to determine the microstructure and raw materials of the samples.Despite the small number of samples, a remarkable variability was revealed in terms of the raw materials and manufacturing processes employed. Overall, three different opacification techniques were documented among the white and grey/blue samples: The Na-rich glasses were opacified using either cassiterite, a typical opacifier for the period, or calcium antimonate, a less common opacifier in the post-Medieval glassmaking. The K-rich white glasses were opacified with the addition of the ashes of animal bones, as suggested by the presence of calcium phosphates, a Byzantine tradition that was possibly also used by Bohemian glassmakers.Finally, the red glasses present certain atypical traits in their microstructure and chemical composition. The samples contain multiple calcite, tin oxide and lead oxide particles. The colour is due to copper, which could only be identified with the application of TEM analysis, in the form of copper oxide nanoparticles.The present study highlights the complicated traditions employed for the production of opaque glass in the post-Medieval European workshops and it underscores the need for a more thorough study of related material.

Compositional and Morphological Investigations of Roman Glass from Cremation Deposits at Birdoswald Fort on Hadrian’s Wall, UK

Several different types of burial were identified during the excavation of the Roman military cemetery associated with the fort at Birdoswald, on Hadrian’s Wall (UK). Fragments of glass vessels and glass beads were recovered from many of the cremation deposits, as they were commonly used during cremation rituals, and many of these had been affected by heat. X-ray fluorescence spectroscopy and scanning electron microscopy were used to investigate the raw materials, colorants and opacifiers employed to produce the glass assemblage. Most of the large fragments are transparent with a blue-green colour, with a composition typical of recycled glass. The smaller fragments are from beads and are coloured and sometimes opaque. Colourants and opacifiers characteristic of Roman glass were added in this glass formulation, including cobalt-based compounds (blue glass), copper alloys (green glass), white calcium antimonate, and yellow lead antimonate. The multianalytical approach of this research has allowed for the distinguishing of the extreme depletion of sodium on the surface of the melted glass fragments due to the exposure to high temperatures during the cremation process, followed by surface weathering in a burial environment. Based on the chemical composition of the bulk of the samples, a model of high temperature viscosity of glass was applied in order to assess the cremation temperature in the pyre, providing relevant information about funerary rituals and cremation technology in Roman Britain.

Study on antimony cake as a technogenic raw material for the production of antimony oxides

In the process of hydrometallurgical and pyrometallurgical production of antimony at the Kadamzhai antimony plant of the Kyrgyz Republic, large-tonnage waste was generated: tailing sand, matte, slag, off-balance ore, cakes, furnace fragments, and electrolytes in salt warehouses. The waste cake is poorly studied; accordingly, the elemental and phase compositions of antimony cake have not been established. In this regard, it was noted that antimony in the cake occurs in the form of calcium antimonate and antimony hydroxide. The content of antimony in the mine tailings cakes is from 3.53 to 4.4%, with a high content of iron (27.5%) and sodium (8.86%). Based on the established elemental and phase compositions, a chemical matrix of antimony cake was compiled. The equilibrium compositions were calculated and the concentration distribution of the main elements of the cake (Fe, Na, Si, Sb) and their compounds in the gas phase was found depending on the temperature of the destruction of the solid phase. It was found that condensed antimony oxides are formed in the range of 1098 - 1348 K. Taking into account the range of temperatures for decomposition of the solid phase, a two-stage smelting of antimony cake is proposed (melting and cupellation). The conversion of antimony cake sulfides from the gas phase into a solution was carried out based on a study of the system: antimony sulfide- manganese (IV) dioxide- sulfuric acid - sodium chloride. The pH value and the redox potential (Eh) of the solution were calculated. It is noted that the sulfur compounds of antimony from the cake are converted to antimony oxychloride with the formation of antimony (III) oxide in an alkaline medium. The use of sodium chloride as a chlorinating agent of antimony sulfur compounds does not lead to the formation of toxic phosgene and hydrogen sulfide; in the solid phase, elemental sulfur is released, which is important for minimizing the technogenic load of pollutants on the environment.

Calcium Positively Mediates Blue Light-Induced Anthocyanin Accumulation in Hypocotyl of Soybean Sprouts.

Soybean sprouts are a flavorful microgreen that can be eaten all year round and are widely favored in Southeast Asia. In this study, the regulatory mechanism of calcium on anthocyanin biosynthesis in soybean sprouts under blue light was investigated. The results showed that blue light, with a short wavelength, effectively induced anthocyanin accumulation in the hypocotyl of soybean sprout cultivar “Dongnong 690.” Calcium supplementation further enhanced anthocyanin content, which was obviously inhibited by LaCl3 and neomycin treatment. Moreover, exogenous calcium changed the metabolism of anthocyanins, and seven anthocyanin compounds were detected. The trend of calcium fluorescence intensity in hypocotyl cells, as well as that of the inositol 1,4,5-trisphosphate and calmodulin content, was consistent with that of anthocyanins content. Specific spatial distribution patterns of calcium antimonate precipitation were observed in the ultrastructure of hypocotyl cells under different conditions. Furthermore, calcium application upregulated the expression of genes related to anthocyanin biosynthesis, and calcium inhibitors suppressed these genes. Finally, transcriptomics was performed to gain global insights into the molecular regulation mechanism of calcium-associated anthocyanin production. Genes from the flavonoid biosynthesis pathway were distinctly enriched among the differentially expressed genes, and weighted gene co-expression network analysis showed that two MYBs were related to the accumulation of anthocyanins. These results indicated that calcium released from apoplast and intracellular stores in specific spatial-temporal features promote blue light-induced anthocyanin accumulation by upregulation of the expression of genes related to anthocyanin synthesis of “Dongnong 690” hypocotyl. The findings deepen the understanding of the calcium regulation mechanism of blue light-induced anthocyanin accumulation in soybean sprouts, which will help growers produce high-quality foods beneficial for human health.

Calcium antimonate: A new discovery in colour palette of Paestum wall paintings

During a restoration and diagnostic campaigns carried out on Paestum funerary slabs belonging to the Lucanian funerary art, calcium antimonate (CaSb2O6) was detected for the first time in the pictorial layers. This artificial pigment, widely employed as opacifier both in ancient glass and glaze covering clay objects, was found in the wall paintings, regardless of the colour, supporting the hypothesis of an intentional addition of calcium antimonate to the pigments and the involvement of ceramic painters.A multi-analytical approach was performed on 32 funerary slabs (6th – 3rd century BCE), currently located at the National Archaeological Museum of Paestum (Italy) using both polarized light microscopy and environmental scanning electron microscopy equipped with energy dispersive X-ray spectrometer, micro X-ray fluorescence, micro Raman spectroscopy, Fourier Transform Infrared spectroscopy and powder X-ray diffraction.The results confirmed the use of a limited number of pigments, usually applied with fresco technique, although in many cases the stratigraphy of the painted layer showed morphology of mezzo fresco technique, but no organic binders were found. The hues of vegetal decorations were obtained using green earth, sometimes Egyptian blue mixed with yellow ochre, carbon and bone blacks, and orpiment. The alteration of green earth and other iron-containing pigments are likely responsible for the discolouration of the original hues. In red paints, hematite and red ochre are frequently associated with ilmenite, a typical volcanic mineral. Egyptian blue was used in blue paints while in black paints it was mixed with carbon and bone black pigments.

First insights into the archaeometric analysis of the Los Amores Mosaic in C\xe1stulo (Linares, Spain): the Judgement of Paris

This paper discusses results obtained from in situ analysis of the tesserae of the Roman mosaic of Los Amores (Cástulo site, Linares, Spain) dating back to the turn of the 1st to the 2nd century AD. Specifically, it focuses on the scene The Judgment of Paris. In view of the exceptional state of preservation of the mosaic, from which very few tesserae had fallen off, non-invasive methods with portable Micro Raman Spectroscopy (MRS) and hand-held X-ray fluorescence (hXRF) and data assessment by use of principal component analysis and binary representations were selected. The results obtained allow to evaluate both the analytical method and the portable equipment used, as well as to classify the raw materials, the colouring agents and the opacifiers used. MRS analysis proved crucial for the identification of stone tesserae (ironstones, carbonate and siliciclastic rocks) and for the identification of the type of glasses used (soda-lime-silicate and lead type glasses) based on the analysis of two detached tesserae. hXRF analysis of the glass tesserae identified both colouring agents (Co, Cu, Pb, Zn) and opacifiers (calcium antimonate). The data obtained lend themselves to an assessment of the degradation process that threaten the integrity of the mosaic. The identification of tessera made of specific stone materials (especially ironstone) and of lead glass tesserae suggest the existence of a mosaic workshop in the Upper Guadalquivir (Eastern Andalusia, Spain).

Applications of Raman spectroscopy in art and archaeology

Applications of Raman spectroscopy in art and archaeology

Preliminary Thermal Investigations of Calcium Antimonate Opacified White Glass Tesserae

Calcium antimonate (in the hexagonal or cubic form) dispersed in the glass matrix is an artificially synthesized phase commonly documented as opacifier for white glasses during the Roman period. Glasses of this type occasionally contain variable amounts of lead oxide. There is no consensus about the origin and role of the lead component in white glasses, whether it was functional to modify the workability of the glass and/or to help the precipitation of the particles, or whether it was an unintentional pollutant introduced with the raw materials. A group of lead and lead-free white mosaic tesserae from the fourth-century CE villa of Noheda in Spain were analyzed by differential scanning calorimetry (DSC) and high temperature X-ray diffraction (HTXRD) to evaluate the impact of variable amounts of lead oxide in the precipitation of calcium antimonate on the viscosity of the glass. The analyzed glasses show thermal events that have been related to the composition of the glass via multicomponent linear regression model. CaSb2O6 and Ca2Sb2O7 formed in the glass during the cooling phase and the glass was not reheated. Lead oxide influences the thermal behavior of the glass, lowering the onset temperatures of all the events, implying a more cost-effective production process. We propose that lead was added intentionally or that lead-bearing raw materials were selected specifically by the ancient glass artisans.

Potential Use of Incineration Bottom Ash in Construction: Evaluation of the Environmental Impact

Knowledge of the long-term leaching behavior of potentially harmful substances is crucial for the assessment of the environmental compatibility of reusing municipal solid-waste incineration bottom ash (MSWI BA) in construction, i.e., as a road base layer. BA fractions obtained from wet-processing aiming at the improvement of environmental quality were used to investigate the mobility of relevant substances. Eluates from laboratory-scaled leaching procedures (column percolation and lysimeters) were analyzed to learn about the long-term release of substances. Unsaturated conditions and artificial rainwater (AR) were used in the lysimeter tests to simulate field conditions. In addition, batch test eluates were generated at usual liquid-to-solid ratios (L/S) for compliance testing purposes. A variety of cations and anions was measured in the eluates. The wet treatment reduces the leaching of chloride and particularly sulfate by more than 60%. The release of typical contaminants for the treated MSWI BA such as the heavy metals Cu and Cr was well below 1% in the conducted leaching tests. An increase in the Sb concentration observed in the lysimeter experiments starting at L/S 0.75 L/kg and in the column experiment at L/S 4 L/kg is assumed to be related to decreasing concentrations of Ca and thus to the dissolution of sparingly soluble calcium antimonate. The same leaching mechanism applies with V, but the concentration levels observed are less critical regarding relevant limit values. However, on the long term the behavior of Sb could be problematic for the application of MSWI BA in construction.Graphic

Post-15th century European glass beads in southern Africa: Composition and classification using pXRF and Raman spectroscopy

A hundred and twenty-seven glass beads found at the archaeological sites in southern Africa were analysed using pXRF and Raman spectroscopy. The beads are identified as European productions on the basis of their composition and morphology. Six identified glass groups are soda-based plant ash (61%), potash-rich wood ash (14%), synthetic soda (8%), mixed alkali (4%), lead-soda (22%) and natron (4%). Except for soda-based plant ashes and natron (outliers), all the groups date back to the 19th century. Calcium antimonate (Ca2Sb2O7) detected in most of the soda-based plant ash glasses (87%) indicated that some of the beads had been imported from Europe since the 17th century.

Host sensitized tunable luminescence of single phase white light emitting Ca2Sb2O7:Eu3+ phosphors

A series of Eu3+ doped calcium antimonate (Ca(2−x)Sb2O7:xEu3+, x = 0, 0.05, 0.07, 0.09, 0.1, 0.2 mol%) phosphors were synthesized via high-temperature solid-state reaction method. The structural and optical characterizations of the prepared samples were done using X-ray diffraction (XRD), scanning electron microscope (SEM), ultraviolet–visible-near infrared (UV–Vis-NIR) absorption spectroscopy, photoluminescence excitation and emission spectra, and luminescence decay measurements of the phosphors. X-ray diffraction spectrum confirmed the phase purity and orthorhombic weberite structure of the samples. Excitation spectrum suggests that the prepared phosphors can be effectively excited by UV (300 nm/330 nm), NUV (393 nm) and blue (464 nm) light-emitting diodes (LEDs). Under 330 nm ultraviolet excitation, calcium antimonate host exhibits a broad blue emission band, while Eu3+ doped Ca2Sb2O7 samples exhibit blue emission band of host and characteristic emission bands of Eu3+ ions resulting in a tunable near white light emission. The energy transfer mechanism from host to activator ions is explained. Under rare earth excitations of 393 nm and 464 nm, the samples exhibit strong reddish-orange emission. Concentration dependence of emission intensity was studied and the critical energy transfer distance of Eu3+ ions in Ca(2−x)Sb2O7:xEu3+ phosphors was calculated. The concentration quenching of emission intensity was found to be due to dipole–dipole interaction. The Commission International de L’Eclairage coordinates (CIE), color purity, correlated color temperature (CCT), and luminescence lifetimes of the samples were also evaluated. The results indicate that through careful engineering of the dopant concentration and also by changing the excitation wavelength, emission color can be tuned from red to white which envisages the prepared phosphors as a promising candidate in solid-state lighting and display fields.

Non‐invasive on‐site Raman study of polychrome and white enamelled glass artefacts in imitation of porcelain assigned to Bernard Perrot and his followers

AbstractBernard Perrot produced sophisticated glass objects from ~1666–1709 in Orléans, particularly white enamelled artefacts and ruby glass. We present here the first non‐invasive Raman study of 16 polychrome and white enamelled glass artefacts that are assigned to Bernard Perrot or his followers. These glasses belong to the museum collections at Orléans and Sèvres in France. The prominent characteristic of these artefacts is their white bodies that were produced in imitation of porcelain. The small thickness of enamel applied to these glasses imposes the use of a high magnification (×200) long working distance microscope objective for Raman analysis. Pigments and opacifiers were identified, and the production technology was discussed. White opacification was found to be obtained by three compounds: calcium phosphate (bone opacification) for blown utensils, calcium antimonate for figurines, and cassiterite for thin enamels. The use of characteristic arsenic‐rich European cobalt was identified in the blue enamels with the characteristic Raman signature of lead arsenate apatite as observed for the 17th and 18th century French soft‐paste porcelains and Limoges enamels. The easy Raman detection of arsenic‐rich phases also allows on‐site identification of ruby glasses produced according to Perrot's technique (formation of Au° colloids by reaction initiated with an arsenic salt). The amount and crystallinity of calcium phosphate being variable appears to be a potential tool to discriminate between different production periods or workshops.

Novel synthesis and optical properties of CaSb2O6 nanoparticles via thermal decomposition of thioacetate precursor

A new molecular precursor Ca[SbO(SCH2COO)Cl H2O] was synthesized from the reaction of calcium thioacetate with SbCl3 in (1:1) ratio. The precursor was characterized by elemental analyses, infrared spectra (IR), and thermal analyses (TGA). IR spectra indicated that thioacetate chelates Sb in a binegative bidentate manner via thiol sulfur and carboxylate oxygen after deprotonation. TGA results indicated that the precursor decomposes in three steps.Calcium antimonate (CaSb2O6) was synthesized from the thermal decomposition of the molecular precursor at 250 °C in air. The calcination product was characterized by X-ray diffractions (XRD), scanning electron microscope (SEM), and transmittance electron microscope (TEM). The results of X-ray diffractions indicated the formation of calcium antimonate nanoparticles which crystallizes in hexagonal system. The crystallite size was found to be 32 nm. Electron microscopes (SEM and TEM) indicated the formation of aggregates of spherical nanoparticles that forms rod like shape. The optical band gap (Eg) measurements showed allowed direct electronic transition. The determined Eg value is 3.9 eV, which is larger than the bulk.

Multi-analytical approach to the study of the European glass beads found in the tombs of Kulumbimbi (Mbanza Kongo, Angola)

The glass bead assemblages recovered during the 2014 excavations of the ruins of Kulumbimbi located in Mbanza Kongo (Angola) were analyzed by means of a multi-analytical minimally invasive methodology, which includes handheld X-ray fluorescence (hXRF), variable pressure scanning electron microscope coupled with energy dispersive X-ray spectrometry (VP-SEM-EDS), micro-Raman spectroscopy and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Chemical data indicate that cobalt, copper, iron and manganese ions were used to produce the blue, green, reddish-brown and black hues, respectively. Lead arsenates, calcium phosphate, calcium antimonate, lead stannate, cassiterite and Pb-Sb-Sn oxide were used as opacifying agents. Chondrite-normalized trace element distribution and chondrite-normalized rare earth element patterns were used to determine the sand source used in the production of the different glass bead types. These distributions were also used to identify the manufacture location of the glass beads with previously unknown origin and production date. Based on the data collected, the glass beads from types 16, 20, 22, 24, 25, 46 and 47 have been assigned as Venetian.

Calcium changes in Robinia pseudoacacia pulvinar motor cells during nyctinastic closure mediated by phytochromes.

Potassium pyroantimonate precipitation, transmission electron microscopy, and X-ray microanalysis were used to investigate the subcellular localization of loosely bound calcium in Robinia pseudoacacia pulvinar motor cells during phytochrome-mediated nyctinastic closure. Calcium localization was carried out in pulvini collected in white light 2h after the beginning of the photoperiod, immediately after a red light or a far-red light pulse applied 2h after the beginning of the photoperiod and after 15 or 25min of darkness respectively. Calcium antimonate precipitates were found in all the pulvinar tissues from the epidermis to the vascular bundle, independent of the light treatment. At subcellular level, precipitates were found mainly in the intercellular spaces, the inner surface of the plasma membrane, cytoplasm, colloidal vacuoles, and nuclei. Red light enhanced the nyctinastic closure of leaflets and caused an asymmetric distribution of cytosolic calcium precipitates between the extensor and flexor motor cells. Both the number and area of the cytosolic calcium precipitates drastically increased in the extensor cells compared to the flexor motor cells. Red light had a rapid and transient effect on the distribution of cytosolic calcium precipitates, which occurred during or at the end of the irradiation, before leaflet closure. By contrast, the distribution of cytosolic loosely bound calcium was similar between the extensor and flexor motor cells after irradiation with far-red light. Our results demonstrate that red light causes specific calcium mobilization in pulvinar motor cells and suggest the involvement of cytoplasmic Ca2+ as a second messenger for phytochrome during nyctinastic closure.

The combined use of Raman and micro‐X‐ray diffraction analysis in the study of archaeological glass beads

AbstractThis study proposes a new nondestructive methodology that combines micro‐Raman spectroscopy and micro‐X‐ray diffraction (μ‐XRD), complemented by variable pressure scanning electron microscopy coupled with energy dispersive X‐ray spectrometry, to determine the composition of glass artifacts and the manufacturing techniques employed in their production. The use of micro‐Raman spectroscopy revealed that most samples belong to the alkaline glass family. Chemical analysis also allowed the identification of the main colorants used in the manufacture of the glass beads in this study. Dark blue and turquoise glass were colored using cobalt ions and copper ions, respectively. Amber or light brown hues were produced using the iron–sulfur amber chromophore. Iron ions were also used to produce green, yellow, cream‐colored gray, and black hues. White glass was produced using calcium antimonate phases. These compounds, identified by micro‐Raman spectroscopy and μ‐XRD, were also used as opacifying agents. This study highlights the importance of using micro‐Raman spectroscopy in the study of ancient glass artifacts. In fact, micro‐Raman spectroscopy not only allows the determination of the glass family of heavily degraded samples but was also found to be the only technique capable of identifying evidences of the rearrangement of the silicate network following selective leaching. The combined use of micro‐Raman spectroscopy and μ‐XRD permitted the identification of the opacifying agents and heat treatment used in the manufacture of the opaque glass beads in this study.

Ancient Roman nano-technology: Insight into the manufacture of mosaic tesserae opacified by calcium antimonate

Opaque mosaic glass tesserae containing calcium antimonates from Ancient Messene, Greece (1st–4th century CE) were investigated by scanning electron microscopy, Raman spectroscopy and X-ray diffraction. Both trigonal CaSb2O6 and cubic Ca2Sb2O7, with crystallite diameters below 1 μm, were identified as opacifying agents. To better understand ancient technologies, we prepared model glasses that were opacified by crystallisation via a secondary heat treatment, by direct crystallisation during the melting process, or by the addition of pre-reacted calcium antimonate to a base glass. We found that direct crystallisation replicated the antique glass artefacts most accurately.We demonstrated that 0.2 wt% of nucleating agents like TiO2 and SnO2 already exert significant influence on the crystallisation behaviour of calcium antimonates. Secondary scattering centres such as silica and carbonates contribute to the optical appearance. Concurrently, we reproduced opaque white glass ceramics in a reconstructed, wood-fired, Roman-type glass furnace built by Wiesenberg (2014).

Something old, something new: the late antique mosaics from the catacomb of San Gennaro (Naples)

Naples assumed an important political and economic role within the region of Campania during the late antique period. LA-ICP-MS data of 285 glass tesserae from the catacomb of San Gennaro in Naples confirm that the surge in building activities in the late fourth and early fifth century CE was accompanied by imports of new materials for the production of mosaic tesserae. Our results from Naples identify a substantial number of Jalame-like Levantine glasses for which there is no parallel within the Italian Peninsula. Only few scattered examples of this type of base glass are found among the published data from Aquileia, Ravenna and the Villa of Faragola, pointing to a link between the supply of glass and the sites' connectivity and economic strength. This seems to have changed after the fifth century. Elemental analyses, combined with SEM-EDS and micro-Raman indicate that the mosaics dating from the fourth to the eighth/ninth century CE in the catacombs of San Gennaro were overwhelmingly made from reused first- to fourth-century Roman base glasses opacified with calcium antimonate. The reuse and recycling of Roman glass and Roman tesserae is a common feature of mosaic assemblages in Italy more generally. The definition of a Roman spectrum tesserae reference group revealed this dependence on old Roman material throughout the first millennium CE.

Lines, spots and trails: a microscopic and mineralogical study of antimonate-opacified glass beads from Lofkënd, Albania

This study focuses on a group of decorated glass beads (twelfth–tenth century BC), belonging to a larger assemblage that was excavated from the prehistoric burial tumulus at Lofkend, Albania. The bulk glass, opaque glass decorations, and corroded areas were examined and analyzed using variable pressure-scanning electron microscopy with energy-dispersive spectroscopy (VP-SEM-EDS) and X-ray diffraction (XRD). The four glass beads analyzed were made using a plant ash-based alkali and colored with an iron containing chromophore which gave the glass its dark green color. Calcium antimonate was the predominant white opacifier used. Sodium antimonate was found as the opacifier in one sample. Its occurrence is likely accidental and formed due to a low concentration of calcium in the glass. Lead antimonate was identified in one sample and, along with calcium antimonate which was also present, would have acted as an opacifier for the white glass.