VSF 2010 Report - Nabo

pebbles of dense vesicular basalt, as well as some sandstone, were recovered.
This slag deposit is clear evidence of iron smelting. The majority of the residues
assessed were identified as production slags, whilst the SHB’s and hammerscale, in this
context, indicate that primary smithing took place. Over 5kg was identified as iron production
slag. Roughly 1kg of this production slag comes from eight individual accumulations of tap
slag. The presence of technical vitrified materials, representative of some form of lining, may
provide further evidence of smelting activity.
Some tap slag accumulations recorded in this assessment were originally identified as
smithing hearth bottoms due to their size and shape. The tap slag accumulations (mostly
identified in context [204=251=302] were plano-convex in form, leading to the initial misidentification.
On closer inspection, the dense nature, rough under surfaces, large vesicles and
ropy texture of the upper surface (with individual rivulets observed) were cause for these slag
remains to be assigned as tap accumulations. Exposed fractures and fragments of these slag
accumulations often exhibited internal layering indicative of multiple taps.
The majority of the slag assessed from this context, by weight, is undiagnostic.
Despite their fragmentary character, five slag pieces were identified as SHB’s from their
rough convex bases. However, it is possible some of these pieces may represent tap slag
accumulations whose upper surfaces have since fragmented. The undiagnostic flowed slag is
nearly equal in weight to the total weight of production slags. The strong evidence for
smelting would indicate that the flowed slag represents production slags that have become
fragmented with post-depositional processes. The spread of the residues of an extensive area
would help explain the fragmentary, and in cases, undiagnostic nature, of the production
slags. The slag recovered from this context corresponds to finds 31, 97 and 100.
ID. [204=251=302] Mag.
Max. Dimensions (cm)
Min. Dimensions (cm)
L W D L W D
Count
Weight (g)
Undiagnostic * 7 5 3