Geochemical and mineralogical distinctions between Bonnin and Morris (Philadelphia, 1770–1772) porcelain and some contemporary British phosphatic wares

The major element compositions of 15 ceramic sherds from the Bonnin and Morris factory site were determined by electron microprobe. Thirteen samples are phosphatic; the others consist of (a) “soapstone” (magnesian/plombian) and (b) true porcelain, and are interpreted as exotic artifacts, as is one compositionally distinct (relatively SiO₂‐poor, P₂O₅+CaO‐rich) phosphatic sample. Although long considered to be virtually indistinguishable from Bow porcelain (London: ca. 1747–1776), the phosphatic Philadelphia wares have a relatively low mean CaO/P₂O₅ ratio (3.3 versus 3.8; molecular proportions) and high alumina content (6.6 versus 5.4 wt % Al₂O₃). Furthermore, unlike Bow, the Bonnin and Morris samples contain calcic plagioclase (bytownite), and in some instances, an orthoclase‐rich ternary feldspar. The preservation of calcic plagioclase indicates that Philadelphia porcelain was fired at (rather than above) the thermal minimum in the An‐SiO₂‐C₃P system, although the presence of Na (and other fluxes) in these wares precludes the exact determination of the maximum firing temperature from this phase diagram. These wares are also distinctive insofar as the phosphate and melt phases can contain small amounts of lead; they have bulk lead contents of approximately 0.1–1.2 wt % PbO. This component has not been detected in the body of Bow or other contemporary British phosphatic porcelains. Their principal similarity lies in the fact that both wares contain sulfate. In addition, the glazes on Bonnin and Morris porcelain (e.g., PbO ∼ 35–50 wt %; SnO₂ ∼ 1–2%) compositionally resemble those used at Bow. If feldspar is formed at all, then Al‐poor phosphatic porcelain (or those with low CaO/P₂O₅ ratios) will have comparatively low modal calcic plagioclase contents, thereby allowing the rapid depletion of this mineral via resorption by the melt phase during vitrification. Such appears to have been the case for analyzed Bow porcelain, which is therefore interpreted to have been overfired (sensu lato) relative to its Philadelphia counterpart. Conceivably, calcic plagioclase could be preserved in low‐Al wares that were fired only briefly at vitrification temperatures. Given the role of firing history in governing the mineralogy of porcelain, compositional criteria are more reliable for distinguishing these wares. © 2001 John Wiley & Sons, Inc.     

Sagged phosphatic Nantgarw porcelain (ca. 1813–1820): Casualty of overfiring or a fertile paste?

Nantgarw phosphatic (bone-ash) porcelain (ca. 1813–1820) is renowned for its translucency and the high quality of its enamel decoration. However, only a small proportion of its wares (perhaps 10%) were successfully fired due to sagging (body distortion) and other problems. This indicates that: (1) In terms of its potential for generating a minimum melt, the Nantgarw paste had an unusually fertile composition, or (2) Nantgarw's staff had difficulties in controlling kiln temperatures, so that its wares tended to be overfired. This issue has been addressed using analytical data for sherds excavated from the factory site. Detailed modal, petrographic, and geochemical data demonstrate that extensively sagged wasters contain a high proportion (∼43–63 vol %) of a former melt phase but are surprisingly porous (7–25 vol % pores). In terms of minimum melt generation, the sagged samples have a more fertile bulk composition than their successfully fired counterparts. Most of the wasters contain subsolidus anorthite (∼An₉₅) enclosed by a melt phase with (once corrected for entrained silica polymorph crystallites) a eutectic (minimum melt) composition. The anorthite, however, was completely resorbed by the melt in some of the sagged samples, which subsequently crystallized liquidus anorthite that displays a quenched morphology. These samples were therefore fired above (T_max <1430°C, as estimated from melt compositions) the eutectic (T∼1290°C) in the anorthite–tricalcium phosphate–silica system. The fact that other wasters contain subsolidus anorthite and a minimum melt shows that firing at the eutectic did not guarantee a successful firing, regardless of the melt fertility of the paste. It is likely that the duration of firing near T_max and character of the object (i.e., flatware vs. hollow-ware) were also important variables in this regard. In addition to producing their well-known phosphatic wares, Nantgarw's proprietors apparently also experimented with silicious pastes with compositions akin to true porcelain. Some of silicious sherds found at the site have a lead-bearing (∼15 wt % PbO) glaze, indicating that they survived an early, high temperature biscuit firing, after which they were fired at lower temperature in the glost kiln (i.e., a “soft-paste type” firing sequence). Evidence that the Nantgarw kiln could achieve temperatures in the order of 1400°C further suggests that these silicious sherds are b.f. wasters. © 1999 John Wiley & Sons, Inc.     

From London to Liverpool: Evidence for a Limehouse–Reid porcelain connection based on the analysis of sherds from the Brownlow Hill (ca. 1755–1767) factory site

The diversity of Brownlow Hill porcelains of the W^m Reid & Co. era is due to the remarkably wide range in the composition of their pastes and glazes and inferred firing conditions relative to the initial vitrification temperature. Sixteen of 21 analyzed sherds from the factory site are bone‐ash wares that display large variations in their bulk chemical composition. The remaining samples have silicious‐aluminous (akin to “stone china” sensu Richard Pococke in 1750) and silicious‐aluminous‐calcic (“S‐A‐C”) compositions that resemble Limehouse (London) and Pomona (Staffordshire) porcelains produced during the 1740s. The mineralogy of the Brownlow Hill S‐A‐C sherds suggests firing at a relatively high temperature (T_max approaching 1400°C, based on relations on the SiO₂‐Al₂O₃‐CaO phase diagram), thereby obscuring the identity of some of the ingredients (e.g., the source of CaO) used in their manufacture. Limehouse and Brownlow Hill may have been linked through the activities of William Ball, who is mentioned in connection with both factories, or indirectly via former Limehouse staff later employed at the Pomona factory, located not far from a W^m Reid & Co. branch factory in Shelton, Stoke‐on‐Trent. In terms of a time line, knowledge of these pastes appears to have spread first from London to Staffordshire, and then to Liverpool. © 2003 Wiley Periodicals, Inc.     

Nicholas Crisp's “Porcellien”: A petrological comparison of sherds from the Vauxhall (London; ca. 1751–1764) and Indeo Pottery (Bovey Tracey,Devonshire; ca. 1767–1774) factory sites

The character of porcelain wares made by Nicholas Crisp early and late in his career was assessed using microchemical and petrographic data for sherds excavated from the sites of the factories he operated at Vauxhall and Bovey Tracey. The results indicate that, over time, Crisp increasingly made use of diverse types of pastes as he struggled to produce a commercially viable line of porcelain. Based on the analysis of a limited number of samples, he appears to have largely restricted himself at Vauxhall to using soapstone (Mg‐rich)‐ and flint‐glass (Pb‐rich) frit‐bearing pastes that varied in the amount of calcite they contained. He also experimented with Mg+Pb‐rich pastes at Bovey Tracey, but included a novel ingredient (barite) and varied the proportion of other minor constituents (e.g., bone ash), apparently in an effort to resolve some of the firing problems that plagued him at Vauxhall. In addition, Crisp appears to have produced bone ash (phosphatic) porcelain at Bovey Tracey, and, in collaboration with William Cookworthy, the proprietor of the Plymouth factory, fired a range of true porcelain (Si+Al‐rich) pastes. Bulk compositional data indicate that Crisp's diopside‐bearing Mg+Pb‐rich wares were derived from pastes containing talc and calcite rather than dolomite. The mineralogy of these and some contemporary magnesian/plombian porcelains are interpreted using the SiO₂‐CaO‐MgO phase diagram. This diagram shows that these wares can form and preserve diopside (Ca‐Mg silicate) given suitable bulk CaO contents and kiln‐firing temperatures. Phosphatic sherds from Bovey Tracey are compositionally distinct (lower SiO₂ and higher Al₂O₃ and bone‐ash components) from a single bone‐ash sample from Vauxhall, indicating that Crisp experimented with novel bone‐ash pastes, and was not positively influenced by the Vauxhall phosphatic recipe, if indeed one existed. True porcelains from Bovey Tracey have more extreme SiO₂/Al₂O₃ ratios (= 2.0 [two sherds]; 4.5 [one sherd]) than their Plymouth/Bristol counterparts (SiO₂/Al₂O₃ = 2.3–3.0). Collectively, the analytical data underscore the experimental—and ultimately unsuccessful—character of the diverse wares produced by Nicholas Crisp. © 2000 John Wiley & Sons, Inc.     

Assessing and correcting the effects of the chemical weathering of potsherds: A case study using soft-paste porcelain wasters from the Longton Hall (Staffordshire) factory site

Unglazed soft-paste porcelain wasters from the Longton Hall factory site are variably depleted (75–80 rel %) in CaO relative to comparatively insoluble components (e.g., Al₂O₃, TiO₂) due to the dissolution of wollastonite (CaSiO₃, a pyroxenoid) by subsurface water. The degree of desilicification is variable (0–45 rel % SiO₂). Petrographic data and element-abundance plots suggest that these were the principal effects of the chemical weathering process in most samples. The preferential dissolution of a single phase in the unglazed Longton Hall sherds permits the semiquantitative “reversal” of weathering phenomena. Alteration effects can be corrected using porosity–volume data to constrain the amount of wollastonite originally present in the weathered sherds. The original compositions of the unglazed wasters are bracketed by arithmetically “adding back” the missing pyroxenoid components according to two endmember assumptions concerning element mobility: (1) the total leaching of wollastonite components and (2) the preferential leaching of wollastonite-derived CaO. These calculations—particularly the latter—yield results that compare favourably with the compositions of relatively unaltered (wollastonite-bearing), glazed samples from the Longton Hall site. Given the potential susceptibility of archaeological ceramics to chemical weathering, it would seem prudent that these phenomena be carefully assessed, and corrected where possible, so that analytical data for these artifacts can be judiciously interpreted. © 1998 John Wiley & Sons, Inc.     

Deep Fractionation of Clinopyroxene in the East Pacific Rise 13°N: Evidence from High MgO MORB and Melt Inclusions

Mid-ocean ridge basalts (MORBs) from East Pacific Rise (EPR) 13°N are analysed for major and trace elements, both of which show a continuous evolving trend. Positive MgO–Al2O3 and negative MgO–Sc relationships manifest the cotectic crystallization of plagioclase and olivine, which exist with the presence of plagioclase and olivine phenocrysts and the absence of clinopyroxene phenocrysts. However, the fractionation of clinopyroxene is proven by the positive correlation of MgO and CaO. Thus, MORB samples are believed to show a “clinopyroxene paradox”. The highest magnesium-bearing MORB sample E13-3B (MgO=9.52%) is modelled for isobaric crystallization with COMAGMAT at different pressures. Observed CaO/Al2O3 ratios can be derived from E13-3B only by fractional crystallization at pressure >4 ±1 kbar, which necessitates clinopyroxene crystallization and is not consistent with cotectic crystallization of olivine plus plagioclase in the magma chamber (at pressure ~1 kbar). The initial compositions of the melt inclusions, which could represent potential parental magmas, are reconstructed by correcting for post-entrapment crystallization (PEC). The simulated crystallization of initial melt inclusions also produce observed CaO/Al2O3 ratios only at >4±1 kbar, in which clinopyroxene takes part in crystallization. It is suggested that MORB magmas have experienced clinopyroxene fractionation in the lower crust, in and below the Moho transition zone. The MORB magmas have experienced transition from clinopyroxene+plagioclase+olivine crystallization at >4±1 kbar to mainly olivine+plagioclase crystallization at <1 kbar, which contributes to the explanation of the “clinopyroxene paradox”.     

Mineralogical and Geochemical Constraints on the Sediment Sources of Late Stone Age Pottery from the Birimi Site,Northern Ghana

The mineralogy and bulk chemical compositions of 15 Kintampo (Late Stone Age) potsherds from the Birimi site on the Gambaga Escarpment and eight samples of local sediment were determined with the intent of characterizing these wares and identifying the material used in their manufacture. Sediment from clay pits still used by potters north of the escarpment contains iron‐rich laterite clasts (100 × XFeO_t = 100 × FeO_t/[FeO_t + Al₂O₃ + SiO₂] ≥10). Sedimentary clasts in stream sediments are relatively siliceous and iron‐poor (100 × XFeO_t < 10). Bulk geochemical data together with the compositions of lithic clasts (laterite, siltstone/sandstone) link the pottery to sediment sources, including escarpment sediments not presently used by Ghanaian potters. Fresh granite clasts found in some of the sherds were not found in the analyzed sediment samples, although some of their distinctive mineralogical constituents (e.g., variably barian alkali feldspar) are present. The analytical data suggest that pots found at Birimi were made locally by mixing escarpment sediment with clay and stream sediment brought in from below the escarpment. This contrasts with present‐day practice, whereby the pots themselves are imported. The place where Birimi pottery was made and the outcrop source of aluminous sediment (mudstone with an “escarpment” trace element signature) used in these wares, however, remain unidentified. © 2013 Wiley Periodicals, Inc.     

Hydrogeochemical assessment of surface and groundwater resources of Korba coalfield,Central India: environmental implications

The present study assesses the impact of coal mining on surface and groundwater resources of Korba Coalfield, Central India. Accordingly, water samples collected from various sources are analyzed for major ions, trace elements, and other mine effluent parameters. Results show that the groundwater samples are slightly acidic, whereas river water and mine water samples are mildly alkaline. Elevated concentrations of Ca²⁺, Na⁺, HCO₃ ^?, and SO₄ ^2? alongside the molar ratios (Ca²⁺+Mg²⁺)/(SO₄ ^2?+HCO₃ ^?) <1 and Na⁺/Cl^? >1 suggest that silicate weathering (water-rock interaction) coupled with ion exchange are dominant solute acquisition processes controlling the chemistry of groundwater in the study area. The overall hydrogeochemistry of the area is dominated by two major hydrogeochemical facies (i.e., Ca–Cl–SO₄ and Ca–HCO₃). Analysis of groundwater and river water quality index (GRWQI) elucidates that majority (82%) of samples are of “excellent” to “good” category, and the remaining 12% are of “poor” quality. Similarly, the effluent water quality index (EWQI) indicates that 6 out of 8 samples belong to excellent quality. Concentration of trace element constituents such as As, Zn, Cu, Cr, and Cd is found to be well within the stipulated limits for potable use, except for Fe, Mn, and Pb. Suitability of water samples for irrigation purpose, established using standard tools like Wilcox and USSL diagrams, reveal “excellent to permissible” category for majority of the samples. The present study also substantiates the effectiveness of the measures implemented for the treatment of mine effluent water.     

Metasomatic origin of garnet xenocrysts from the V. Grib kimberlite pipe,Arkhangelsk region,NW Russia

This paper presents new major and trace element data from 150 garnet xenocrysts from the V. Grib kimberlite pipe located in the central part of the Arkhangelsk diamondiferous province (ADP). Based on the concentrations of Cr₂O₃, CaO, TiO₂ and rare earth elements (REE) the garnets were divided into seven groups: (1) lherzolitic “depleted” garnets (“Lz 1”), (2) lherzolitic garnets with normal REE patterns (“Lz 2”), (3) lherzolitic garnets with weakly sinusoidal REE patterns (“Lz 3”), (4) lherzolitic garnets with strongly sinusoidal REE patterns (“Lz 4”), (5) harzburgitic garnets with sinusoidal REE patterns (“Hz”), (6) wehrlitic garnets with weakly sinusoidal REE patterns (“W”), (7) garnets of megacryst paragenesis with normal REE patterns (“Meg”). Detailed mineralogical and geochemical garnet studies and modeling results suggest several stages of mantle metasomatism influenced by carbonatite and silicate melts. Carbonatitic metasomatism at the first stage resulted in refertilization of the lithospheric mantle, which is evidenced by a nearly vertical CaO-Cr₂O₃ trend from harzburgitic (“Hz”) to lherzolitic (“Lz 4”) garnet composition. Harzburgitic garnets (“Hz”) have probably been formed by interactions between carbonatite melts and exsolved garnets in high-degree melt extraction residues. At the second stage of metasomatism, garnets with weakly sinusoidal REE patterns (“Lz 3”, “W”) were affected by a silicate melt possessing a REE composition similar to that of ADP alkaline mica-poor picrites. At the last stage, the garnets interacted with basaltic melts, which resulted in the decrease CaO-Cr₂O₃ trend of “Lz 2” garnet composition. Cr-poor garnets of megacryst paragenesis (“Meg”) could crystallize directly from the silicate melt which has a REE composition close to that of ADP alkaline mica-poor picrites. P-T estimates of the garnet xenocrysts indicate that the interval of ～60–110 km of the lithospheric mantle beneath the V. Grib pipe was predominantly affected by the silicate melts, whereas the lithospheric mantle deeper than 150 km was influenced by the carbonatite melts.     

Structural CO2 in the Apatite of the Late Cretaceous Phosphorite Resources in Egypt: Effect on the Crystal Chemistry and Geologic Implications

Abstract: Phosphorite deposits in Egypt, known as the Duwi Formation, are a part of the Middle East to North Africa phospho‐genic province of late Cretaceous to Paleogene age. Based on the petrographical observation, the phosphatic grains in the phosphorites are classified into phosphatic mudclasts and phosphatic bioclasts. Both of them are composed of francolite. The structural CO₂ contents in the francolite range from 3.3 to 7.2 % with an average of 5.3 %. Results indicated that the substitution with CO₃^2‐ of PO₄^3‐ in the francolite decreases the unit cell volume and a‐cell dimension, and increases the c/a ratio. Effect is more obvious in the a‐cell dimension; therefore, it is more significant in distinction between the different apatite species. Lack of covariance between structural CO₂ contents in the francolite and the carbonate minerals contents may render the supposition that the phosphorites formed as a result of replacement of preexisting calcareous sediments is doubtful. Similarity in CO₂ content in both weathered and fresh samples indicates that the structural CO₂ content in the phosphorites is not affected by weathering, and reflects the conditions and CO₂ concentration of the depositional environment. Similarity in mineralogy and CO₂ contents in the different phosphatic grains and higher CO₂ content in the Egyptian phosphorites compared with the authigenic phosphates of Peru margin, which formed by the same mechanism as the Duwi phosphorites, suggest that the phosphatic grains in the Duwi Formation were francolitized during diagenesis by introducing CO₂ from the surrounding pore water and diagenesis took place at an elevated temperature. Scattered values of structural CO₂ contents suggest the reworking origin of the phosphatic grains in the late Cretaceous phosphorites in Egypt.     

Molecular and isotopic characterization of organic samples from the wreck of the Saint-Etienne merchant ship (XVIIIth century): Identification of pitch,fat, hair and sulfur

The wreck U Pezzo, excavated within the Saint Florent Gulf in northern Corsica was identified as the pink, Saint Etienne, a merchant ship which sank on January 31, 1769. In order to determine the composition of organic materials used to coat the hull or to waterproof different parts of the pink, a study of several samples, using molecular biomarker and carbon isotopic analysis, was initiated. The results revealed that the remarkable yellow coat, covering the outside planks of the ship’s bottom under the water line, is composed of sulfur, tallow (of ox and not of cetacean origin) and black pitch which corresponds to a mixture called “couroi” or “stuff”. Onboard ropes had been submitted to a tarring treatment with pitch. Hairs mixed with pitch were identified in samples collected between the two layers of the hull or under the sheathing planking. The study also provides a key model for weathering of pitch, as different degrees of degradation were found between the surface and the heart of several samples. Accordingly, molecular parameters for alteration were proposed. Furthermore novel mixed esters between terpenic and diterpenic alcohols and the free major fatty acids (C_14:0, C_16:0, C_18:0) were detected in the yellow coat.     

The use of soil geochemistry in outlining phosphate deposits, northern and southern Venezuela

Phosphate deposits have been outlined in Falcón State (Northern Venezuela) and Táchira State (Southwestern Venezuela) using geochemical soil methods.The phosphate deposits located in Falcón State constitute lenses and masses interbedded with Tertiary limestone and shales. The area is covered by a thick soil with few outerops and the region is characterized by typical tropical rain forest. Soil samples taken every 1000 m across complete stratigraphic sequences were analyzed for P₂O₅ content. An anomalous area with a P₂O₅ content ranging from 3.19% to 9.04% was outlined accompanied by areas with less than 0.83% of P₂O₅. More than 11 million metric tons of commercial phosphatic rock were associated with this anomaly.In Táchira State several stratigraphic sequences of potentially phosphatic rocks with a thick cover of black soil were geochemically investigated. Soil samples taken each 10 m were analyzed for P₂O₅. A sequence of phosphatic rock was outlined showing a P₂O₅ content varying between 7.3% and 9.2%. Apparently the sequence is interbedded with phosphate-poor siliceous rocks showing a P₂O₅ content below 2%.As result of this preliminary investigation, expensive trenching, pitting and drilling works can be carefully planned.     

Bismuth‐melt trails trapped in cassiterite–quartz veins

Native bismuth in the form of metallic melt has been considered instrumental to the formation of some metallic ore deposits via a mechanism dubbed the “Liquid Bismuth Collector Model.” Here, we provide petrographical documentation of trail‐forming, μm‐sized blebs of native bismuth in cassiterite–quartz veins from the Santa Bárbara greisen Sn deposit in the Rondônia tin province of northern Brazil. These inclusions suggest the trapping of a Bi melt that took place during vein formation, in a mechanism similar to the entrapment of fluid inclusions.     

A comparative electron microprobe study of “Aeginetan” wares with potential raw material sources from Aegina,Methana, and Poros,Greece

Qualitative stylistic evidence from ceramic vessels and limited petrographic analysis suggested that a distinctive group of ceramics with visible inclusions of biotite (Gold Mica Fabric) was produced on the island of Aegina, Greece, during the Middle Helladic and Late Helladic I periods. To quantitatively evaluate this provenance, we sampled all potential source rocks on Aegina, Methana, and Poros. Electron microprobe analysis of amphibole in these samples revealed that each of these volcanic centers has its own unique mineralogical signature. Comparative analyses of amphibole in Zerner's original stylistic “Gold Mica Fabric” type sample with the reference samples reveal that two sherds are Aeginetan. Three additional sherds from this sample may have a non‐Aeginetan provenance, probably from a back‐arc setting outside the Saronic Gulf. These results suggest that the hypothesis of a single source production site for Aeginetan Ware should be reexamined. © 2002 Wiley Periodicals, Inc.     

Re‐creation of the 1744 Heylyn and Frye ceramic patent wares using Cherokee clay: Implications for raw materials,kiln conditions,and the earliest English porcelain production

Porcelain wares have been produced following the directions contained in the Heylyn and Frye patent of 1744, using Cherokee clay and a lime‐alkali glass frit. The wares were fired to the bisque (˜ 950°C), glazed using a clay‐glass mixture, and then fired to a “heat‐work” level of Orton cone 9–90° deflection at 150°C per hour (1279°C). Modal mineralogy comprises Caplagioclase and two glass phases, one relict frit and the other a melt phase. The bulk chemistry of the body comprises 64.3 wt % SiO₂, 21.7 wt % Al₂O₃, and 5.6 wt % CaO. Molecular ratios are SiO₂:Al₂O₃ 5.0 and SiO₂:CaO 10.7. It is concluded that the patent, whose significance has been questioned over many years, was a practical working recipe, that close comparison may be made with porcelains of the “A”‐marked group, and that the patent represents a remarkable landmark in English ceramic history. © 2004 Wiley Periodicals, Inc.     

Polymetamorphism in high‐T metamorphic rocks: An example from the central Appalachians

Contact metamorphism associated with mafic intrusives is one of several mechanisms that has been invoked to produce extensive high‐temperature (HT) metamorphism and associated partial melting of the crust. Indisputable evidence for polymetamorphism in these settings can be difficult to decipher because both melt loss and retrogression (i.e. rehydration) can erase or obscure the records of earlier HT metamorphism by modifying HT mineral parageneses and compositions. Here, a combination of detailed field and petrographical observations, inverse mineral thermometry, and thermodynamic forward modelling is used to delineate the polymetamorphic history of migmatites from the Smith River Allochthon (SRA) in the central Appalachians. Bulk rock geochemical data suggest that some metapelitic samples lost a significant amount of melt during interpreted contact metamorphism with the Rich Acres gabbro, resulting in a residual bulk composition (<50 wt% SiO₂, ~30 wt% Al₂O₃). Garnet cores (Grt1) in SiO₂‐depleted samples are interpreted to grow during this HT contact metamorphism, with Fe‐Ti oxide thermometry on spinel inclusions in Grt1, cordierite–garnet thermometry, and thermodynamic forward modelling constraining peak P–T conditions during contact heating of the migmatites to ~800ºC and ～0.5 GPa. This is associated with an inferred peak assemblage prior to melt loss of crd+kfs+pl+grt+bt+spl (mag+usp+hc)+ilm+sil+qtz+melt. Garnet in SiO₂‐depleted samples has a distinct high‐Ca rim (Grt2), which appears to record a younger metamorphic event. A combination of substantial melt loss and later rehydration appears to be a major control on the ability of SiO₂‐depleted samples to faithfully record evidence for this polymetamorphism. The tectonic implications of this younger metamorphic event are not entirely clear, but it appears to record renewed burial and heating of the SRA sometime after the Taconic orogeny, which may be related to either the neo‐Acadian or Alleghanian orogenies.     

Speciation and weathering of copper in “copper red ruby” medieval flashed glasses from the Tours cathedral (XIII century)

Three “copper ruby red” (or “flashed”) glasses from the St Gatien cathedral in Tours (windows from the XIII century) were investigated at the Cu K-edge by synchrotron X-ray fluorescence microscopy and μ-XANES/EXAFS spectroscopies. The spectra are compared to XANES/EXAFS spectra collected for modern glasses synthesized at various O₂ fugacities. Two main types of red glasses are present in Tours, which show a distinct Cu speciation. In the first type (“plaqués”), Cu is present as sub-micron metallic nucleates, which coexist with monovalent Cu linear moieties (30:70 at.%). In contrast, the glasses of the other type (“feuilletés”) show mostly monovalent Cu (together with some evidence for metallic Cu in the edge region of the XANES).The plaqués glasses appear to have been synthesized at lower O₂ fugacity and higher temperatures to promote homogeneous nucleation of metallic Cu. A relative enrichment in Al (provided by the addition of orthoclase in the melt) greatly enhances the glass durability by decreasing the melt peralkalinity by a factor of ∼4. In contrast, the feuilletés were equilibrated at much higher O₂ fugacities. Hence, metallic Cu, despite being scarce in that glass, is not at equilibrium and could have well been added on purpose during the melt cooling. It is proposed that a technique called ‘tourage’ could have been used to help create the micron scale greenish and red layers. The feuilleté glasses are also weathered at their surface, promoting the formation of amorphous Cu(II) species related to a Cu sulphate.     

Silicification,silicosis, polymerization,and aluminosis in geocrystallochemistry of silicates and aluminosilicates

Quantum-chemical interpretations of differentiation of the “normal” magmatic melt (the “Bowen's fork”) show certain defects in the traditionally crystallochemical interpretations of mineral structures and of the sequence of crystallization of minerals. The “dynamic unit,” in transitions from phase to phase and from lattice to lattice, proves to be the uncharged SiO₂ molecule and not the SiO₄ tetrahedron, which is but a static architectural detail of crystal structures. Different mechanisms and types of silicification (figs. 3-8), condensation and structures of the chains (figs. 9-14), structures of zeolites and other aluminosilicates (figs. 14, 17, 18), and the quantumchemical representation of corundum, as “molecular” Al₂O₃, illustrate further reevaluations of traditionalism in mineralogy.     

Exceedance of air quality standards resulting from pyro-metallurgical production of copper: a case study, Bor (Eastern Serbia)

This study represents air quality data of SO₂ and As concentrations around the mining–metallurgical complex Bor (Serbia) from 1994 to 2008. Daily and annual SO₂ concentrations greatly exceed current air quality standards in the studied area. The “hot spot” with the highest SO₂ and As annual concentrations during 15 years was the urban-industrial area (the town core). Daily SO₂ concentrations and meteorological parameters during the period from 2005 to 2008 were statistically analysed to develop suitable prediction equations for daily SO₂ concentrations. Anode copper production is an important but not the only factor that has influence on SO₂ concentrations. By stepwise multiple linear regression analysis, it was determined that daily SO₂ concentrations are most influenced by maximum wind gust, relative humidity and air temperature at all the measuring sites. The prediction equations of daily SO₂ concentrations represent a good model with regression coefficients from 0.854 to 0.926 at all the measuring sites. Correlation analysis showed that eastern and western winds increase SO₂ concentrations, thus increasing the health risk of the inhabitants in the study area.     

Preliminary study of the microstructure and mineralogy of 12th and 13th century ceramics,Samsat, Southeastern Turkey

The mineralogy and microstructure of 12th and 13th century ceramics from Samsat, Turkey were examined with an X-ray diffractometer and scanning electron microscope. There is a highly vitrified interlayer between the glaze and body in these sherds that probably accounts for the high durability of these ceramics. the lower vitrification and uniformity of the body in these ceramics suggests that leftover glaze was not mixed with paste during manufacture. Finally, the presence of tabular forsterite in the pores of the body points to the use of magnesium rich raw materials.