Mineralogical And Chemical Investigations Of Bloomery Slags From Prehistoric (8th Century Bc To 4th Century Ad) Iron Production Sites In Upper And Lower Lusatia,Germany

More than 400 fayalitic bloomery slags from prehistoric iron production sites in Upper and Lower Lusatia, eastern Germany, as well as bog iron ore samples and intermediary samples of the smelting process, were analysed by chemical and mineralogical techniques. While the precursor bog iron ores exploited in the two regions under investigation were very similar in composition, consisting of low‐manganese/low‐barium as well as high‐manganese/high‐barium types of ore, pronounced differences in slag composition were detected. Slags from 17 investigated sites in Upper Lusatia showed average P₂O₅ contents between 1 and 3 mass%, whereas slags from 15 investigated sites in Lower Lusatia were generally much richer in phosphorus, reaching values as high as 7 mass% P₂O₅. Since a reasonable correlation exists between calcium and phosphorus contents in the slags of the latter sites, it is conjectured that deliberate addition of CaO to the ore/charcoal charge of the bloomery furnace may have taken place in order to fix the phosphorus in the slags effectively. In many samples, this conjecture is being supported by the detection of a slag mineral Ca–Fe phosphate Ca_9?xFe_1+x(PO₄)₇ that presumably crystallized from a residual phosphorus‐rich melt and shows a cotectic relationship to both Ca‐rich fayalite and wustite, as well as to members of the solid solution series magnetite–hercynite.     

北京万泉寺遗址金代白瓷胎釉配方的锶同位素特征研究

北京丰台万泉寺遗址位于金中都遗址内,遗址出土金代白瓷样品在形制上符合金代定窑白瓷特征。白瓷胎体成分和锶同位素比值综合研究确定了三种制胎原料,其中:高铝黏土原料的锶同位素比值在0.73左右;白云岩化石灰岩原料的锶同位素比值在0.72左右且钙含量较高;草木灰原料的锶同位素比值在0.71左右,且锶含量在1 000 μg/g左右。通过釉层的成分分析及胎釉成分的对比研究,发现釉层主要使用高硅原料与白云岩化石灰岩配制而成,并受到了部分熔融胎体的强烈影响,根据与草木灰关联性较强的P₂O₅含量推断,釉层中可能也含有一定量草木灰。万泉寺遗址白瓷的研究丰富了有关金代定窑白瓷胎釉配方的认识,确认了白云岩化石灰岩为胎釉的主要钙质助熔剂,揭示了草木灰类助熔剂在胎和釉中可能存在各自独立的来源。     

New Data on the Soda Flux Used in the Production of Iznik Glazes and Byzantine Glasses

Previous research has shown that Iznik glazes are characterized by low potash and magnesia contents. It was therefore suggested that the flux used was either a purified plant ash or some unidentified mineral source of soda. More recently, as a result of the detection of small, but significant, amounts of boron and lithium in Byzantine glasses from western Turkey, which also exhibit low potash and magnesia contents, it has been suggested that the source of the flux used was a soda‐rich evaporite associated in some way with the extensive borax deposits in the region. LA–ICP–MS has been used to establish that Iznik glazes also contain similarly small amounts of boron and lithium. The Na/K, Na/Mg, Na/Ca and Na/B ratios for these Iznik glazes are shown to be comparable to the equivalent ratios calculated from published data for waters from a range of Na–HCO₃ type hot springs in western Turkey, with the closest match being to the hot springs around Afyon‐Gazligöl, which is consistent with documentary evidence. It is therefore proposed that the soda‐rich salts produced by evaporating water from these springs to dryness would have provided the flux required for the production of Iznik glazes and high‐boron Byzantine glasses.