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Slag Summary


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Baulk Trim T66 2016 Section







We recovered exceptionally high quantities of slag in T90 in 2017.  We found over 7 kg of slag in T90.  This number is not only high, in and of itself, but is remarkable given the small area from which the slag was recovered.  In total, we excavated an area measuring approximately 8 square meters in 2017, but nearly all the slag found came from a roughly 1.5 square meter section through the floor of EPOC4.

There are three discernible chronological phases in T90 and the quantities of slag recovered correlate to these chronological phases.  The earliest chronological phase is that predating the construction of EPOC4 and consists of Loci 9 and 10.  The middle chronological phase is the functional floor surface of EPOC4, which corresponds to Locus 8.  The latest phase postdates the occupation of EPOC4 and is associated with the construction of a small, rectilinear building over the remains of the front porch of EPOC4.  Nearly all slag found in T90 came from contexts associated with the earliest chronological phase, that predating EPOC4.

We recovered the vast majority of slag from Locus 10, a black, charcoal-heavy, burnt deposit; nearly 800 fragments of slag weighting 4.637 kg was recovered from this locus.  All slag found in Locus 10, like all slag recovered from T90, is ferric slag.  This slag contains traces of iron and so is magnetic.  This slag is not indicative of iron smelting though, but rather results from the extraction of copper ores from mixed copper and iron deposits.  The extraction of copper ore likely is associated with bronze production.  The high quantities of slag recovered from Locus 10 strongly indicate that bronze production was commonly practiced in the area that later became EPOC4.  This conclusion is supported further by the exceptionally high number of crucible fragments found in this same deposit, many of which preserve traces of slag adhered to the ceramic’s interior surface (PC20170022, PC20170023, PC20170051).  Furthermore, we found a number of examples of pan tiles that likely were used for smelting copper ore (PC20170055).  These pan tiles exhibited one vitrified surface, with vitrification being limited to a discrete area.  Some pan tiles even had ferric slag adhered to such vitrified surfaces.

While we recovered less slag from the floor of EPOC4 (Locus 8), we still found high quantities of slag in this deposit; we found nearly 1 kg of slag in EPOC4’s floor, or 14% of all slag found in T90.  Therefore, we conclude that bronze production occurred in the area of EPOC4, prior to the building’s construction, and that such activities continued in the same place, which became the front porch of EPOC4, in the subsequent occupational phase.

There is little evidence for metal production postdating the occupation of EPOC4.  We found only 15 g of slag in the loci associated with the later, rectilinear structure overlaying EPOC4’s floor.  This accords with the ceramic evidence as well; while high volumes of coarseware, specifically crucible fragments, were recovered from the lower loci of the trench, associated with and predating EPOC4, we recovered far more impasto in the upper loci associated with the rectilinear structure.

In conclusion, the high quantities of slag found in T90 are strong evidence for copper extraction and bronze production in the area of EPOC4’s front porch.  Bronze production occurred in this area in the first two occupational phases, however, following the abandonment of EPOC4, bronze production stopped in this particular area.  The extraction of copper likely changed locations, perhaps to the non-elite house and adjacent shed excavated in 2012-2013.  These structures date to the late 7th century and in the adjacent shed, we found nearly 10 kg of ferric slag.

Descriptive Variable Value(s)
Document Type Trench Book Entry
Start Page 271
End Page 274
Trench Book Entry Date 2017-08-08
Entry Year 2017
Trench T90
Title T90 (KRK) other, p. 271-274
Entry Type Other
Property or Relation Value(s)
Temporal Coverage
[Standard: Dublin Core Terms]
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Suggested Citation

Katharine R. Kreindler. "T90 (2017-08-08):271-274; Other from Italy/Poggio Civitate/Tesoro/Tesoro 90/T90 2017". (2017) In Murlo. Anthony Tuck (Ed.) . Released: 2017-10-04. Open Context. <>

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