VSF 2010 Report - Nabo

that iron production and smithing were taking place at this site. The evidence for smelting is
pronounced in contexts [204=251=302], [319], [324], [6057] and [7012]. The prevalence of
smelting slag in these deposits is concurrent with the increases in flowed slag and
undiagnostic residues, making it clear that these are slag-rich deposits. Many of these deposits
also produce technical vitrifications that are thought to represent constructions relating to
smelting, and/or smithing. The technical vitrifications indicate that a siliceous material was
formed during smelting that bears impression of the furnace shape. The slag-stone
conglomerate, and flattish stone recovered in connection with the residues, provides some
information concerning the subterranean environment of at least one furnace. The curvature of
some technical vitrifications provide an idea about the size of the lower parts of the furnace.
These deposits also see a pronounced deposition of ferruginous concretions, many of which
are thought to be reduced iron ore fragments. Further analysis is necessary to confirm that
these iron concretions are indeed ore bodies. The microscopic and chemical analysis shows
that there may have been changes in temperature and atmosphere in the smelting conditions
that produced under which the slag formed. It is not clear whether the changes in conditions
represent certain technological practices, or an unstable smelting environment. The ternary
phase diagram reveals that the smelting slags were produced between 1100-1200°C in the
fayalitic range. These temperatures confirm that any reduction of ore would have successfully
produced metallic iron. It also reveals that high-temperature nature of the smelting taking
place. The tap slag accumulations suggest that slag tapping was part of the process of
smelting iron. It is not clear yet, however, whether this slag-tapping technology was a feature
throughout the time iron was being smelting. The charcoal fragments identified show that
betula was the fuel used for smelting. This would agree with the preliminary results of
ongoing research into fuel usage at Vatnsfjörður (Mooney 2008, 2009). The conifer
impression revealed in the microscopy of the undiagnostic fragment needs further
investigation to determine whether this wood was a fuel, or the fragment itself derives from
another pyrotechnical process not related to ferrous metallurgy.
There is also evidence for smithing at Vatnsfjörður. Smithing hearth bottoms show
distinct similarities in their size and shape. The spheroidal hammerscale identified in
association with the SHB’s and smelting residues indicates that primary smithing was taking
place. Although there is evidence of bloom refining on site, the partially refined iron blooms
recovered from [7059] need to undergo further chemical analysis in order to confirm that they
were produced at Vatnsfjörður. The burnt bone fragments found in two contexts may be the
result of re-deposition, or may be directly related to smithing activites that were taking place,
as has been demonstrated at other contemporaneous sites in Scandinavia.
The assessment of the archaeometallurgical residues from Vatnsfjörður demonstrates
that both smelting and smithing were taking place at the site. It is difficult to articulate the
scale of the smelting and smithing without further understanding the temporal relationship
between deposits. Should the residues represent a constrained time frame, the residues would
suggest that smelting on site far exceeded any domestic demands. Further investigation into
the residues should yield a greater understanding on the smelting and smithing activities
taking place at Vatnsfjörður.
Evaluation
The archaeometallurgical residues from Vatnsfjörður form the second slag assemblage in
Viking period Iceland that have been comprehensively studied. As such, they represent an
important insight into the technological activities that were taking place. Relatively little work
has been undertaken into the metallurgical debris of archaeological sites in Iceland,
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