The Bremner Porcellanite Quarry and Working Floor near the Hawkdun Range is a significant Archaic period stone working site, and the largest porcellanite quarry in Otago. It is one of several sites found in the interior of Otago, dating to the earliest phase of New Zealand’s prehistory (c. 1250-1500 AD), and has cultural, archaeological and scientific significance.

Archaeological knowledge of Māori habitation in Central Otago is relatively sparse. Stone tools appear to have been used to process moa carcasses. Moa-hunters used silcrete and porcellanites as cutting tools. Silcrete and porcellanite are found only in the south of the South Island, and most quarries are small (300m2 to 2000m2). The greatest concentration of silcrete and porcellanite in Otago is in a broad band from Nenthorn to the Manuherikia Valley. Archaeologist Atholl Anderson reports on records of 30 silcrete quarries and 15 porcellanite quarries for Otago, Southland, and South Canterbury. The main tools were flakes and blades, both struck from quarried cores. Most moa hunter’s flake tools are ‘primary flakes’ selected because they had an existing sharp edge. The Bremner quarry and those at Rough Block and Oturehua are among the largest. Anderson writes that the size of the quarries may reflect ‘frequency of repeated use.’

Alexander Mutch of the New Zealand Geological Survey recorded the site in March 1960. He described what appeared to be a ‘working floor of “burnt mudstone”’ with ovens nearby. Graeme Mason of the Anthropology Department of the University of Otago revisited the site in March 1974. The quarry has two patches of rock about 700 metres apart, each covering 0.6 hectares. Archaeologist Jill Hamel describes them as ‘bare pink areas’ in the tussocks at the edge of a terrace at the head of the Manuherikia Valley. The site covers about 1 ½ acres and shows evidence of quarry pits and a working floor on a south west facing terrace covered in tussock and herbfields. The site is largely undisturbed except for a bulldozer cut made in the late 1960s or early 1970s. The site looks to have been ‘heavily used over a long period of time.’

Archaeologist Tim Thomas relocated the site in March 2016. He described the face of the terrace as having several small outcrops of exposed porcellanite, the debris from which had tumbled downslope. Much of the seam of porcellanite is buried however, and the ground surface is covered in tussock, Spaniard and matagouri. Most of the stone working occurred on the uppermost edge of the terrace with surrounding pits dug down on top of the seam. The location where this is most visible is marked by several orange erosion scars exposing dissolving porcellanite formations just to the west of the track. A large circular quarry pit (approx. 5m diameter, 1m deep) is the most obvious feature, however flakes can be found over much of the flat/gently sloping area to the north of the terrace face. Vegetation covers most of the flaking floor, but the pit feature is relatively exposed. This pit is surrounded by heaped dumps of waste material, and is filled with flaked stone. Large greywacke hammerstones were noted, as were blade fragments and other debitage. Where water flows on site the porcellanite is dissolving to a light orange mud and flakes are found sitting atop this material suggesting some artefact transport in these areas. The porcellanite exhibits a wide range of colours but is mostly a light greyish purple, weathering or oxidising to orange; some yellow ochre coloured pieces occur. In 2018, the site is included within a pastoral lease.