The work of Máximo Neira Avendaño (1990;1968) is distinguished as being the earliest systematic Archaic Period excavations in the Arequipa highlands. In the mid-1960s Neira excavated at seven preceramic sites close to the Sumbay train station, including several rock shelters, known as Sumbay-1 through Sumbay-7. The sites were later renamed "Ccollpa-Sumbay" by Eloy Lináres Malaga in 1984 (1990;1992) as part of the CONCYTEC survey.

The Sumbay area lies 42 km to the south-east of the Chivay source across the pampa and it is 9.3 hours from the obsidian source area by the hiking model. The main cavern, SU-3, is a rock shelter that is concealed in narrow canyon that cuts through the puna. This rock shelter measuring 15m across, 11m deep, and 6m in height at the dripline, was badly looted in the 1930s, and Neira's excavations focused on the remaining intact portions of the cave. The cave is known for exceptional rock art panels featuring both petroglyphs, ochre pictographs, and a variety of animal species including elongated camelids, a hunting puma, humanoid figures, and surithe Andean ostrich.

Seven excavation pits were placed in the main shelter, SU-3. Pit 5 produced obsidian samples in every level along with a large number of tools made from pitchstone, a dull vitreous material formed from weathered obsidian that has absorbed water from the environment. Pitchstone has 4-10% water while obsidian has 0.1 - 0.5% water (M. Glascock, 2006 pers. comm.). The source of this pitchstone is probably somewhere near Sumbay and further study of this pitchstone may provide an interesting complement to the chemical characterization of obsidian.

Figure 3-8. Sumbay pitchstone projectile points.

Table 3-8. Sumbay, SU-3 Pit 5. Strata with obsidian samples and associated artifacts(Neira Avendaño 1990: 32-33).

Twenty-five obsidian samples were analyzed from the Sumbay area. Twenty samples from the surface and terreplain of the rock shelter SU-2, two from the surface of the rock shelter SU-3, and 3 from excavations in SU-3, Pit 5 (Burger, et al. 1998: 209;Burger, et al. 2000: 278). All samples turned out to be of the Chivay type. Since stratum 3 was dated to the Middle - Late Archaic transition, the stratum 4 obsidian sample is stratigraphically below than that, so it is probably Middle Archaic in date.