Iron slag is formed as a byproduct of iron smelting. Here a large slag nodule has broken in half, revealing its interior texture. At the archaeological site of Ngre Kataa, large chunks of 'bubbly' slag like this were occasionally found in household and other contexts, away from areas otherwise associated with metal-working activities. Potters at the time of the site's occupation had begun to use crushed iron slag as a tempering agent in their potting clays, which may explain why large nodules were being carried and cached in areas away from metal-working locations. Ngre Kataa, June, 2008.
View from above of an insitu grinding stone (GS 08-03) and a pottery jar (NK 08-176) at the base of excavation level 3 in an area (mound 6) that archaeologists interpret as a metallurgical workshop. The grinding stone has a concave upper surface, partly obscured by unexcavated soil. Roots and rootlets are visible on the right side of the photo. Photo stick marked in 5 cm increments. Arrow pointing north. Site Ngre Kataa. 1 July 2008.
Excavations in units 42N 4W and 44N 4W have exposed clusters of pottery, grinding stones, tuyeres and an area of burned soil associated with metal working at mound 6, Ngre Kataa. Foreground, bottom right, are a partial pottery jar (NK 08-520) and a small flat grinding stone (GS 08-12; partially visible). To the left (west), framed by photo scales, is a burned feature. Next to it sits a hand-held hammerstone (GS 08-11). Above (to the north), a cluster of pottery and a partial tuyere (NK 08-284) are visible along the boundary between excavation units (marked by stakes). To the right of that cluster (east), a grinding stone (GS 08-10) has been pedestaled where it was found, resting with its working surface face down. Two pottery vessels sit at a slightly lower level (NK 08-406). Top center of the photo, at the far end of the excavated area, a cluster of anvil stones is visible (GS 08-05 to 08) in excavation unit 46N 4W. Photo scale adjacent to burned feature marked in 5 cm intervals. View looking north. Site Ngre Kataa. 7 July 2008.
Wide view of excavation unit 44N 6W in an area (mound 6) that archaeologists interpret as a metallurgical workshop. Lower left, below the unit's corner stake (44N 6W), the partial rim of an everted jar (NK 08-408) has been pedestaled. It rests with its rim down. Between it and a large anvil stone (GS 08-25, center photo) is a smaller light-colored stone (GS 08-21) and piece of a jar rim. Another jar rim (NK 08-409) has been pedestaled in place to the left (east) of the anvil stone. Behind the anvil stone, an everted-rim jar (NK 08-407, photo stick in front) has been partially exposed. In the unit's center, to the right of the anvil stone, the rounded edge of a burned feature is visible. To the right (west) and in front (north) of that, a photo scale sits alongside an iron projectile point (SF 08-112). The soil around it has been dampened to aid excavation (dark circular area). To its right (west) is another piece of a worn grinding stone (GS 08-20). Visible in the adjacent units (left, east) is a grindstone (GS 08-10) which has been pedestaled in place and to its right a cluster of pottery and a tuyere (NK 08-284). View looking south. Photo bar marked in 5 cm intervals. Site Ngre Kataa. 7 July 2008.
The body and base of a large pottery bowl has been exposed by exavation in unit 46N 8W. Surrounding this bowl was a cluster of sherds from other pottery vessels, now removed to expose several iron bangles of different shapes and sizes, seen insitu here. Between the bowl and the photo scale is an iron bangle (SF NK 08-169) formed from a spiral-twisted rod. Pedestaled to the right of the bowl (east) is an iron bangle (SF NK 08-140) made from a round rod that was coiled. Visible in the wall behind and to the right of the bowl (north) is a smalled coiled iron bangle made from a flattened piece of iron (SF NK 08-182). This cluster (A) was part of a larger cluster (A-D) of artifacts that archaeologists interpret as a shrine placed in a metallurgical workshop. Rootlets are visible in the wall and floor of the unit. View looking north. Photo scale in 5 cm increments. Site Ngre Kataa. 9 July 2008.
A cluster of four large insitu anvil/grinding stones in an area (mound 6) that archaeologists interpret as a metallurgical workshop. The stone at the bottom of the photo (GS 08-06) was oriented with its grinding surface down (not, therefore, visible in the photo). The middle right stone (GS 08-07) also rested with its most-used grinding surface down. The largest stone (middle, left, GS 08-05) had no clear working surface. The stone at the back (GS 08-08) was associated with a fist-sized round quartz hammerstone, seen insitu slightly above. Later exavations (2009) revealed a perforated pot (NK 09-750), lidded with the base of another pot (NK 09-750), adjacent to but approximately 40 cm below this cluster in the next excavation unit. Photo scale in 5 cm increments. Arrow pointing north, view looking east. Site Ngre Kataa. 3 July 2008.
A small round stone (GS 08-11) rests insitu next to an irregularly shaped area of burned fire-hardened sediment in an area (mound 6) that archaeologists interpret as a metallurgical workshop. The stone has wear consistent with use as a hammerstone. The burned sediment was next to a circular area of soil that showed signs of oxidation through exposure to high heat. A small piece of copper alloy metal lies at the edge of the fire-hardened sediment, to the left of the hammerstone and above the right site of the photo stick. The feature is likely associated with forging activities. Photo scale at bottom marked in 5 cm intervals. View from above, north at top of photo. Site Ngre Kataa. 5 July 2008.
The body and base of a large pottery bowl has been exposed by exavation in unit 46N 8W. Surrounding this bowl was a cluster of sherds from other pottery vessels, now removed to expose several iron bangles of different shapes and sizes, seen insitu here. At the base of the photo, center, is an iron bangle (SF NK 08-169) formed from a spiral-twisted rod. Pedestaled to the right of the bowl (east) is an iron bangle (SF NK 08-140) made from a round rod that was coiled. Visible in the wall behind and to the right of the bowl (north; above the photo scale) is a small coiled iron bangle made from a flattened piece of iron (SF NK 08-182). A smaller bangle-like artifact lies directly above the pot, center photo (north; SF 08-139). This area (cluster A) was part of a larger cluster (clusters A-D) of artifacts that archaeologists interpret as a shrine placed in a metallurgical workshop. Rootlets are visible in the wall and floor of the unit. View from above, north at top of photo. Photo scale in cm increments. Site Ngre Kataa. 9 July 2008.
An arc of orange-red burned features has been exposed in excavation units 46N 8W and 48N 8W in an area (mound 6) that archaeologists interpret as a metallurgical workshop. To the left (west), the body and base of a large pottery bowl (NK 08-522) has been pedestaled insitu. A number of iron bangles surrounded this bowl (cluster A) as part of a large shrine cluster that extended into adjacent units (where the trunk of a small tree is visible, upper left). The base of this cluster was about 20-30 cm above the burned basins exposed in this photo. Center photo, flanked by photo scales, the round rim of a pottery jar is visible in outline. To the right (east) of the burned features, two hammerstones rest insitu next to one another. To the north of the burned features (forward right of the sign board), a zone of white plaster-like sediment is visible. Far right, archaeologist Abass Iddrisu uses a trowel to expose the contours of burned sediment in an adjacent excavation unit. Red and white scale is two meters in length. Arrow pointing north. Site Ngre Kataa. 17 July 2008.
An arc of orange-red burned features has been exposed in excavation units 46N 8W and 48N 8W in an area (mound 6) that archaeologists interpret as a metallurgical workshop. To the left (west), the body and base of a large pottery bowl (NK 08-522) has been pedestaled insitu. A number of iron bangles surrounded this bowl (cluster A) as part of a large shrine cluster (A-D) that extended into adjacent units (where the trunk of a small tree is visible, above left of the sign board). The base of this cluster was about 20-30 cm above the burned basins exposed in this photo. The everted rim of a pottery jar visible in the north wall of the excavation unit (top left) was part of an adjacent cluster (B) that also included iron bangles (SF 08-183 & 184). Center photo, flanked by a photo scale, the round rim of a pottery jar is visible in outline. To the right (east) of the burned features, two hammerstones rest insitu next to one another. To the north of the burned features (forward right of the sign board), a zone of white plaster-like sediment is visible. Red and white scale is two meters in length. Arrow pointing north. Site Ngre Kataa. 17 July 2008.