Obsidian hydration dates were obtained from samples taken from 13 of the tombs, using methods current in the late 1970s.
Earlier work using obsidian hydration dating is now questioned on methodological grounds.
City-states in the agricultural periphery and those with regionally restricted raw materials such as obsidian had a greater emphasis on non-subsistence craft production.
All components of the rock, except the obsidian cobbles, are susceptible to weathering and are easily transformed into clay, as the matrix is quite porous.
Aspects of social organization are addressed through the obsidian data, as are some insights into tool production and by whom.
For obsidian, sampling and analyzing all sources is a realistic goal.
Both of these city-states provide evidence of specialized production, exchange, and consumption of obsidian tools.
The inclusion of more information on the other techniques that are applicable to obsidian studies would have been very useful.
