J.IIC-CG VOLUME 19 (1994)
A Conservation Strategy for a Seventeenth Century Archaeological Site at Ferryland, Newfoundland
Archaeological iron artifacts and associated soil matrix of a seventeenth century Colonial period site at Ferryland, Newfoundland, have been studied with special emphasis on the mineralogy of the corrosion products. Eight soil samples were collected from two areas for physical and chemical characterization. X-ray fluorescence (XRF) and X-ray diffraction (XRD) techniques were used for chemical analysis. Eighteen iron nails, representing different conditions of burial, were analyzed using XRD and X-radiography. Petrographic analyses, using reflected-light microscopy and an electron microprobe, were also performed. The data suggest that resultant corrosion products and overall artifact condition were influenced by the surrounding environment. Soil data indicated that both site areas displayed a high quartz and feldspar concentration with minor clay minerals. Goethite, lepidocrocite, chromite, magnetite, quartz, feldspar and clay mineral phase(s) were identified from the iron nail corrosion products. The latter three components were a product of the environment and not an alteration product. Visual and instrumental observation of both soil and artifacts indicated that stratigraphic levels which represent fill and a burning event over approximately 50% of the excavated area would probably offer the best environment for preservation. Conservation of all ferrous metals was considered to be expensive and impractical for the Ferryland site where approximately 15,000 iron artifacts are excavated per season. The conservation strategy developed for the ferrous metals thus employed both passive and active treatment. Iron nail fragments will be oven dried. An aqueous 1% sodium hydroxide solution will be used for most other ferrous metals, excluding composites. In order to facilitate chloride removal, an immersion time of approximately one year will be required.
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